[PATCH v3 0/8] mfd: watchdog: rtc: New driver for ST's LPC IP

[PATCH v3 0/8] mfd: watchdog: rtc: New driver for ST's LPC IP

[Lee Jones]

ST's Low Power Controller (LPC) controls two devices; watchdog and RTC.
Only one of the devices can be used at any one time, which is enforced
by the correlating MFD driver.
  
This driver set provides everything you need to choose one (and only
one) of the LPC devices to run per I/P block, of which there are two
on the enabled STiH407 h/w.

Version 3:
 - Move Regmap pointer into core device data structure
 - Remove error message from devm_ioremap_resource
  
Version 2:
 - Only calculate keepalive once in probe()
 - Check for a 0 clk_rate
 - Set limits using predefined attributes from watchdog_device
 - CONFIG_PM => CONFIG_SLEEP
 - Call st_wdog_setup() on resume
 - Remove MFD driver -- instead rely on driver probing mechanism
   which continues attempting to bind to different drivers until
   one does not return -ENODEV

Lee Jones (8):
  ARM: multi_v7_defconfig: Enable support for ST's LPC Watchdog
  ARM: multi_v7_defconfig: Enable support for ST's LPC RTC
  ARM: STi: DT: STiH407: Add Device Tree node for the LPC
  watchdog: bindings: Provide ST bindings for ST's LPC Watchdog device
  watchdog: st_wdt: Add new driver for ST's LPC Watchdog
  rtc: bindings: Provide ST bindings for ST's LPC RTC device
  rtc: st: add new driver for ST's LPC RTC
  MAINTAINERS: Add Watchdog and RTC files to STI's maintainer entry

 .../devicetree/bindings/rtc/rtc-st-lpc.txt         |  25 ++
 .../devicetree/bindings/watchdog/st_lpc_wdt.txt    |  38 +++
 MAINTAINERS                                        |   2 +
 arch/arm/boot/dts/stih407-family.dtsi              |  20 ++
 arch/arm/configs/multi_v7_defconfig                |   2 +
 drivers/rtc/Kconfig                                |  12 +
 drivers/rtc/Makefile                               |   1 +
 drivers/rtc/rtc-st-lpc.c                           | 354 +++++++++++++++++++++
 drivers/watchdog/Kconfig                           |  13 +
 drivers/watchdog/Makefile                          |   1 +
 drivers/watchdog/st_lpc_wdt.c                      | 333 +++++++++++++++++++
 11 files changed, 801 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/rtc-st-lpc.txt
 create mode 100644 Documentation/devicetree/bindings/watchdog/st_lpc_wdt.txt
 create mode 100644 drivers/rtc/rtc-st-lpc.c
 create mode 100644 drivers/watchdog/st_lpc_wdt.c

-- 
1.9.1

[PATCH v3 1/8] ARM: multi_v7_defconfig: Enable support for ST's LPC Watchdog

[Lee Jones]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 arch/arm/configs/multi_v7_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
index 7afc0a2..561ca4f 100644
--- a/arch/arm/configs/multi_v7_defconfig
+++ b/arch/arm/configs/multi_v7_defconfig
@@ -274,6 +274,7 @@ CONFIG_WATCHDOG=y
 CONFIG_XILINX_WATCHDOG=y
 CONFIG_ARM_SP805_WATCHDOG=y
 CONFIG_ORION_WATCHDOG=y
+CONFIG_ST_LPC_WATCHDOG=y
 CONFIG_SUNXI_WATCHDOG=y
 CONFIG_MESON_WATCHDOG=y
 CONFIG_MFD_AS3722=y
-- 
1.9.1

[PATCH v3 2/8] ARM: multi_v7_defconfig: Enable support for ST's LPC RTC

[Lee Jones]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 arch/arm/configs/multi_v7_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/multi_v7_defconfig b/arch/arm/configs/multi_v7_defconfig
index 561ca4f..4e45e53 100644
--- a/arch/arm/configs/multi_v7_defconfig
+++ b/arch/arm/configs/multi_v7_defconfig
@@ -405,6 +405,7 @@ CONFIG_RTC_DRV_DS1307=y
 CONFIG_RTC_DRV_MAX8907=y
 CONFIG_RTC_DRV_MAX77686=y
 CONFIG_RTC_DRV_PALMAS=y
+CONFIG_RTC_DRV_ST_LPC=y
 CONFIG_RTC_DRV_TWL4030=y
 CONFIG_RTC_DRV_TPS6586X=y
 CONFIG_RTC_DRV_TPS65910=y
-- 
1.9.1

[PATCH v3 3/8] ARM: STi: DT: STiH407: Add Device Tree node for the LPC

[Lee Jones]

On current ST platforms the LPC controls a number of functions.  This
patch enables support for the LPC Watchdog and LPC RTC devices on LPC1
and LPC2 respectively.

Signed-off-by: David Paris <david.paris@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 arch/arm/boot/dts/stih407-family.dtsi | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/arm/boot/dts/stih407-family.dtsi b/arch/arm/boot/dts/stih407-family.dtsi
index 3e31d32..04448a7 100644
--- a/arch/arm/boot/dts/stih407-family.dtsi
+++ b/arch/arm/boot/dts/stih407-family.dtsi
@@ -7,6 +7,7 @@
  * publishhed by the Free Software Foundation.
  */
 #include "stih407-pinctrl.dtsi"
+#include <dt-bindings/mfd/st-lpc.h>
 #include <dt-bindings/reset-controller/stih407-resets.h>
 / {
 	#address-cells = <1>;
@@ -274,5 +275,24 @@
 
 			status = "disabled";
 		};
+
+		/* Watchdog and Real-Time Clock */
+		lpc@8787000 {
+			compatible = "st,stih407-lpc";
+			reg = <0x8787000 0x1000>;
+			interrupts = <GIC_SPI 129 IRQ_TYPE_EDGE_RISING>;
+			clocks = <&clk_s_d3_flexgen CLK_LPC_0>;
+			timeout-sec = <120>;
+			st,syscfg = <&syscfg_core>;
+			st,lpc-mode = <ST_LPC_MODE_WDT>;
+		};
+
+		lpc@8788000 {
+			compatible = "st,stih407-lpc";
+			reg = <0x8788000 0x1000>;
+			interrupts = <GIC_SPI 130 IRQ_TYPE_EDGE_RISING>;
+			clocks = <&clk_s_d3_flexgen CLK_LPC_1>;
+			st,lpc-mode = <ST_LPC_MODE_RTC>;
+		};
 	};
 };
-- 
1.9.1

[PATCH v3 4/8] watchdog: bindings: Provide ST bindings for ST's LPC Watchdog device

[Lee Jones]

On current ST platforms the LPC controls a number of functions including
Watchdog and Real Time Clock.  This patch provides the bindings used to
configure LPC in Watchdog mode.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 .../devicetree/bindings/watchdog/st_lpc_wdt.txt    | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/watchdog/st_lpc_wdt.txt

diff --git a/Documentation/devicetree/bindings/watchdog/st_lpc_wdt.txt b/Documentation/devicetree/bindings/watchdog/st_lpc_wdt.txt
new file mode 100644
index 0000000..1bdf023
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/st_lpc_wdt.txt
@@ -0,0 +1,38 @@
+STMicroelectronics Low Power Controller (LPC) - Watchdog
+========================================================
+
+LPC currently supports Watchdog OR Real Time Clock functionality.
+
+[See: ../rtc/rtc-st-lpc.txt for RTC options]
+
+Required properties
+
+- compatible 	: Must be one of: "st,stih407-lpc" "st,stih416-lpc"
+				  "st,stih415-lpc" "st,stid127-lpc"
+- reg		: LPC registers base address + size
+- interrupts    : LPC interrupt line number and associated flags
+- clocks	: Clock used by LPC device (See: ../clock/clock-bindings.txt)
+- st,lpc-mode	: The LPC can run either one of two modes ST_LPC_MODE_RTC [0] or
+		  ST_LPC_MODE_WDT [1].  One (and only one) mode must be
+		  selected.
+
+Required properties [watchdog mode]
+
+- st,syscfg	: Phandle to syscfg node used to enable watchdog and configure
+		  CPU reset type.
+- timeout-sec	: Watchdog timeout in seconds
+
+Optional properties [watchdog mode]
+
+- st,warm-reset	: If present reset type will be 'warm' - if not it will be cold
+
+Example:
+	lpc@fde05000 {
+		compatible	= "st,stih416-lpc-watchdog";
+		reg		= <0xfde05000 0x1000>;
+		clocks 		= <&clk_s_d3_flexgen CLK_LPC_0>;
+		st,syscfg	= <&syscfg_core>;
+		timeout-sec	= <120>;
+		st,lpc-mode	= <ST_LPC_MODE_WDT>;
+		st,warm-reset;
+	};
-- 
1.9.1

[PATCH v3 5/8] watchdog: st_wdt: Add new driver for ST's LPC Watchdog

[Lee Jones]

Signed-off-by: David Paris <david.paris@st.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/watchdog/Kconfig      |  13 ++
 drivers/watchdog/Makefile     |   1 +
 drivers/watchdog/st_lpc_wdt.c | 333 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 347 insertions(+)
 create mode 100644 drivers/watchdog/st_lpc_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 08f41ad..a3b483c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -471,6 +471,19 @@ config SIRFSOC_WATCHDOG
 	  Support for CSR SiRFprimaII and SiRFatlasVI watchdog. When
 	  the watchdog triggers the system will be reset.
 
+config ST_LPC_WATCHDOG
+	tristate "STMicroelectronics LPC Watchdog"
+	depends on ARCH_STI
+	depends on OF
+	select WATCHDOG_CORE
+	select MFD_ST_LPC
+	help
+	  Say Y here to include STMicroelectronics Low Power Controller
+	  (LPC) based Watchdog timer support.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called st_wdt.
+
 config TEGRA_WATCHDOG
 	tristate "Tegra watchdog"
 	depends on (ARCH_TEGRA || COMPILE_TEST) && HAS_IOMEM
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index c569ec8..31dd6a0 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_RETU_WATCHDOG) += retu_wdt.o
 obj-$(CONFIG_BCM2835_WDT) += bcm2835_wdt.o
 obj-$(CONFIG_MOXART_WDT) += moxart_wdt.o
 obj-$(CONFIG_SIRFSOC_WATCHDOG) += sirfsoc_wdt.o
+obj-$(CONFIG_ST_LPC_WATCHDOG) += st_lpc_wdt.o
 obj-$(CONFIG_QCOM_WDT) += qcom-wdt.o
 obj-$(CONFIG_BCM_KONA_WDT) += bcm_kona_wdt.o
 obj-$(CONFIG_TEGRA_WATCHDOG) += tegra_wdt.o
diff --git a/drivers/watchdog/st_lpc_wdt.c b/drivers/watchdog/st_lpc_wdt.c
new file mode 100644
index 0000000..4c71027
--- /dev/null
+++ b/drivers/watchdog/st_lpc_wdt.c
@@ -0,0 +1,333 @@
+/*
+ * st-wdt.c - ST's LPC Watchdog
+ *
+ * Copyright (C) 2014 STMicroelectronics -- All Rights Reserved
+ *
+ * Author: David Paris <david.paris@st.com> for STMicroelectronics
+ *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+#include <dt-bindings/mfd/st-lpc.h>
+
+/* Low Power Alarm */
+#define LPC_LPA_LSB_OFF			0x410
+#define LPC_LPA_START_OFF		0x418
+
+/* LPC as WDT */
+#define LPC_WDT_OFF			0x510
+
+static struct watchdog_device st_wdog_dev;
+
+struct st_wdog_syscfg {
+	unsigned int reset_type_reg;
+	unsigned int reset_type_mask;
+	unsigned int enable_reg;
+	unsigned int enable_mask;
+};
+
+struct st_wdog {
+	void __iomem *base;
+	struct device *dev;
+	struct regmap *regmap;
+	struct st_wdog_syscfg *syscfg;
+	struct clk *clk;
+	unsigned long clkrate;
+	bool warm_reset;
+};
+
+static struct st_wdog_syscfg stid127_syscfg = {
+	.reset_type_reg		= 0x004,
+	.reset_type_mask	= BIT(2),
+	.enable_reg		= 0x000,
+	.enable_mask		= BIT(2),
+};
+
+static struct st_wdog_syscfg stih415_syscfg = {
+	.reset_type_reg		= 0x0B8,
+	.reset_type_mask	= BIT(6),
+	.enable_reg		= 0x0B4,
+	.enable_mask		= BIT(7),
+};
+
+static struct st_wdog_syscfg stih416_syscfg = {
+	.reset_type_reg		= 0x88C,
+	.reset_type_mask	= BIT(6),
+	.enable_reg		= 0x888,
+	.enable_mask		= BIT(7),
+};
+
+static struct st_wdog_syscfg stih407_syscfg = {
+	.enable_reg		= 0x204,
+	.enable_mask		= BIT(19),
+};
+
+static struct of_device_id st_wdog_match[] = {
+	{
+		.compatible = "st,stih407-lpc",
+		.data = &stih407_syscfg,
+	},
+	{
+		.compatible = "st,stih416-lpc",
+		.data = &stih416_syscfg,
+	},
+	{
+		.compatible = "st,stih415-lpc",
+		.data = &stih415_syscfg,
+	},
+	{
+		.compatible = "st,stid127-lpc",
+		.data = &stid127_syscfg,
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, st_wdog_match);
+
+static void st_wdog_setup(struct st_wdog *st_wdog, bool enable)
+{
+	/* Type of watchdog reset - 0: Cold 1: Warm */
+	if (st_wdog->syscfg->reset_type_reg)
+		regmap_update_bits(st_wdog->regmap,
+				   st_wdog->syscfg->reset_type_reg,
+				   st_wdog->syscfg->reset_type_mask,
+				   st_wdog->warm_reset);
+
+	/* Mask/unmask watchdog reset */
+	regmap_update_bits(st_wdog->regmap,
+			   st_wdog->syscfg->enable_reg,
+			   st_wdog->syscfg->enable_mask,
+			   enable ? 0 : st_wdog->syscfg->enable_mask);
+}
+
+static void st_wdog_load_timer(struct st_wdog *st_wdog, unsigned int timeout)
+{
+	unsigned long clkrate = st_wdog->clkrate;
+
+	writel_relaxed(timeout * clkrate, st_wdog->base + LPC_LPA_LSB_OFF);
+	writel_relaxed(1, st_wdog->base + LPC_LPA_START_OFF);
+}
+
+static int st_wdog_start(struct watchdog_device *wdd)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+	writel_relaxed(1, st_wdog->base + LPC_WDT_OFF);
+
+	return 0;
+}
+
+static int st_wdog_stop(struct watchdog_device *wdd)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+	writel_relaxed(0, st_wdog->base + LPC_WDT_OFF);
+
+	return 0;
+}
+
+static int st_wdog_set_timeout(struct watchdog_device *wdd,
+			       unsigned int timeout)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+	wdd->timeout = timeout;
+	st_wdog_load_timer(st_wdog, timeout);
+
+	return 0;
+}
+
+static int st_wdog_keepalive(struct watchdog_device *wdd)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(wdd);
+
+	st_wdog_load_timer(st_wdog, wdd->timeout);
+
+	return 0;
+}
+
+static const struct watchdog_info st_wdog_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
+	.identity = "ST LPC WDT",
+};
+
+static const struct watchdog_ops st_wdog_ops = {
+	.owner		= THIS_MODULE,
+	.start		= st_wdog_start,
+	.stop		= st_wdog_stop,
+	.ping		= st_wdog_keepalive,
+	.set_timeout	= st_wdog_set_timeout,
+};
+
+static struct watchdog_device st_wdog_dev = {
+	.info		= &st_wdog_info,
+	.ops		= &st_wdog_ops,
+};
+
+static int st_wdog_probe(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+	struct device_node *np = pdev->dev.of_node;
+	struct st_wdog *st_wdog;
+	struct regmap *regmap;
+	struct resource *res;
+	struct clk *clk;
+	void __iomem *base;
+	uint32_t mode;
+	int ret;
+
+	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
+	if (ret) {
+		dev_err(&pdev->dev, "An LPC mode must be provided\n");
+		return -EINVAL;
+	}
+
+	/* LPC can either run in RTC or WDT mode */
+	if (mode != ST_LPC_MODE_WDT)
+		return -ENODEV;
+
+	st_wdog = devm_kzalloc(&pdev->dev, sizeof(*st_wdog), GFP_KERNEL);
+	if (!st_wdog)
+		return -ENOMEM;
+
+	match = of_match_device(st_wdog_match, &pdev->dev);
+	if (!match) {
+		dev_err(&pdev->dev, "Couldn't match device\n");
+		return -ENODEV;
+	}
+	st_wdog->syscfg	= (struct st_wdog_syscfg *)match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
+	if (IS_ERR(regmap)) {
+		dev_err(&pdev->dev, "No syscfg phandle specified\n");
+		return PTR_ERR(regmap);
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Unable to request clock\n");
+		return PTR_ERR(clk);
+	}
+
+	st_wdog->dev		= &pdev->dev;
+	st_wdog->base		= base;
+	st_wdog->clk		= clk;
+	st_wdog->regmap		= regmap;
+	st_wdog->warm_reset	= of_property_read_bool(np, "st,warm_reset");
+	st_wdog->clkrate	= clk_get_rate(st_wdog->clk);
+
+	if (!st_wdog->clkrate) {
+		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
+		return -EINVAL;
+	}
+	st_wdog_dev.max_timeout = 0xFFFFFFFF / st_wdog->clkrate;
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to enable clock\n");
+		return ret;
+	}
+
+	watchdog_set_drvdata(&st_wdog_dev, st_wdog);
+	watchdog_set_nowayout(&st_wdog_dev, WATCHDOG_NOWAYOUT);
+
+	/* Init Watchdog timeout with value in DT */
+	ret = watchdog_init_timeout(&st_wdog_dev, 0, &pdev->dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to initialise watchdog timeout\n");
+		clk_disable_unprepare(clk);
+		return ret;
+	}
+
+	ret = watchdog_register_device(&st_wdog_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to register watchdog\n");
+		clk_disable_unprepare(clk);
+		return ret;
+	}
+
+	st_wdog_setup(st_wdog, true);
+
+	dev_info(&pdev->dev, "LPC Watchdog driver registered, reset type is %s",
+		 st_wdog->warm_reset ? "warm" : "cold");
+
+	return ret;
+}
+
+static int st_wdog_remove(struct platform_device *pdev)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+
+	st_wdog_setup(st_wdog, false);
+	watchdog_unregister_device(&st_wdog_dev);
+	clk_disable_unprepare(st_wdog->clk);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int st_wdog_suspend(struct device *dev)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+
+	if (watchdog_active(&st_wdog_dev))
+		st_wdog_stop(&st_wdog_dev);
+
+	st_wdog_setup(st_wdog, false);
+
+	return 0;
+}
+
+static int st_wdog_resume(struct device *dev)
+{
+	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
+
+	st_wdog_setup(st_wdog, true);
+
+	if (watchdog_active(&st_wdog_dev)) {
+		st_wdog_load_timer(st_wdog, st_wdog_dev.timeout);
+		st_wdog_start(&st_wdog_dev);
+	}
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(st_wdog_pm_ops,
+			 st_wdog_suspend,
+			 st_wdog_resume);
+
+static struct platform_driver st_wdog_driver = {
+	.driver	= {
+		.name = "st-lpc-wdt",
+		.pm = &st_wdog_pm_ops,
+		.of_match_table = st_wdog_match,
+	},
+	.probe = st_wdog_probe,
+	.remove = st_wdog_remove,
+};
+module_platform_driver(st_wdog_driver);
+
+MODULE_AUTHOR("David Paris <david.paris@st.com>");
+MODULE_DESCRIPTION("ST LPC Watchdog Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

[PATCH v3 6/8] rtc: bindings: Provide ST bindings for ST's LPC RTC device

[Lee Jones]

On current ST platforms the LPC controls a number of functions including
Watchdog and Real Time Clock.  This patch provides the bindings used to
configure LPC in RTC mode.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 .../devicetree/bindings/rtc/rtc-st-lpc.txt         | 25 ++++++++++++++++++++++
 1 file changed, 25 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/rtc/rtc-st-lpc.txt

diff --git a/Documentation/devicetree/bindings/rtc/rtc-st-lpc.txt b/Documentation/devicetree/bindings/rtc/rtc-st-lpc.txt
new file mode 100644
index 0000000..aaf9855
--- /dev/null
+++ b/Documentation/devicetree/bindings/rtc/rtc-st-lpc.txt
@@ -0,0 +1,25 @@
+STMicroelectronics Low Power Controller (LPC) - RTC
+===================================================
+
+LPC currently supports Watchdog OR Real Time Clock functionality.
+
+[See: ../watchdog/st_lpc_wdt.txt for Watchdog options]
+
+Required properties
+
+- compatible 	: Must be one of: "st,stih407-lpc" "st,stih416-lpc"
+				  "st,stih415-lpc" "st,stid127-lpc"
+- reg		: LPC registers base address + size
+- interrupts    : LPC interrupt line number and associated flags
+- clocks	: Clock used by LPC device (See: ../clock/clock-bindings.txt)
+- st,lpc-mode	: The LPC can run either one of two modes ST_LPC_MODE_RTC [0] or
+		  ST_LPC_MODE_WDT [1].  One (and only one) mode must be
+		  selected.
+
+Example:
+	lpc@fde05000 {
+		compatible	= "st,stih416-lpc-watchdog";
+		reg		= <0xfde05000 0x1000>;
+		clocks 		= <&clk_s_d3_flexgen CLK_LPC_0>;
+		st,lpc-mode	= <ST_LPC_MODE_RTC>;
+	};
-- 
1.9.1

[PATCH v3 7/8] rtc: st: add new driver for ST's LPC RTC

[Lee Jones]

ST's Low Power Controller (LPC) controls two devices; watchdog and RTC.
Only one of the devices can be used at any one time.  This is enforced
by the correlating MFD driver.  This portion of the driver-set controls
the Real Time Clock.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/rtc/Kconfig      |  12 ++
 drivers/rtc/Makefile     |   1 +
 drivers/rtc/rtc-st-lpc.c | 354 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 367 insertions(+)
 create mode 100644 drivers/rtc/rtc-st-lpc.c

diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
index f15cddf..ca509e8 100644
--- a/drivers/rtc/Kconfig
+++ b/drivers/rtc/Kconfig
@@ -1417,6 +1417,18 @@ config RTC_DRV_SIRFSOC
 	  Say "yes" here to support the real time clock on SiRF SOC chips.
 	  This driver can also be built as a module called rtc-sirfsoc.
 
+config RTC_DRV_ST_LPC
+	tristate "STMicroelectronics LPC RTC"
+	depends on ARCH_STI
+	depends on OF
+	select MFD_ST_LPC
+	help
+	  Say Y here to include STMicroelectronics Low Power Controller
+	  (LPC) based RTC support.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called rtc-st-lpc.
+
 config RTC_DRV_MOXART
 	tristate "MOXA ART RTC"
 	depends on ARCH_MOXART || COMPILE_TEST
diff --git a/drivers/rtc/Makefile b/drivers/rtc/Makefile
index c8ef3e1..6dbb7d9 100644
--- a/drivers/rtc/Makefile
+++ b/drivers/rtc/Makefile
@@ -149,4 +149,5 @@ obj-$(CONFIG_RTC_DRV_WM8350)	+= rtc-wm8350.o
 obj-$(CONFIG_RTC_DRV_X1205)	+= rtc-x1205.o
 obj-$(CONFIG_RTC_DRV_XGENE)	+= rtc-xgene.o
 obj-$(CONFIG_RTC_DRV_SIRFSOC)	+= rtc-sirfsoc.o
+obj-$(CONFIG_RTC_DRV_ST_LPC)	+= rtc-st-lpc.o
 obj-$(CONFIG_RTC_DRV_MOXART)	+= rtc-moxart.o
diff --git a/drivers/rtc/rtc-st-lpc.c b/drivers/rtc/rtc-st-lpc.c
new file mode 100644
index 0000000..f1344ac
--- /dev/null
+++ b/drivers/rtc/rtc-st-lpc.c
@@ -0,0 +1,354 @@
+/*
+ * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer
+ *
+ * Copyright (C) 2014 STMicroelectronics Limited
+ *
+ * Author: David Paris <david.paris@st.com> for STMicroelectronics
+ *         Lee Jones <lee.jones@linaro.org> for STMicroelectronics
+ *
+ * Based on the original driver written by Stuart Menefy.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public Licence
+ * as published by the Free Software Foundation; either version
+ * 2 of the Licence, or (at your option) any later version.
+ */
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/platform_device.h>
+#include <linux/rtc.h>
+
+#include <dt-bindings/mfd/st-lpc.h>
+
+/* Low Power Timer */
+#define LPC_LPT_LSB_OFF		0x400
+#define LPC_LPT_MSB_OFF		0x404
+#define LPC_LPT_START_OFF	0x408
+
+/* Low Power Alarm */
+#define LPC_LPA_LSB_OFF		0x410
+#define LPC_LPA_MSB_OFF		0x414
+#define LPC_LPA_START_OFF	0x418
+
+/* LPC as WDT */
+#define LPC_WDT_OFF		0x510
+#define LPC_WDT_FLAG_OFF	0x514
+
+struct st_rtc {
+	struct rtc_device *rtc_dev;
+	struct rtc_wkalrm alarm;
+	struct resource *res;
+	struct clk *clk;
+	unsigned long clkrate;
+	void __iomem *ioaddr;
+	bool irq_enabled:1;
+	spinlock_t lock;
+	short irq;
+};
+
+static void st_rtc_set_hw_alarm(struct st_rtc *rtc,
+				unsigned long msb, unsigned long  lsb)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	writel(1, rtc->ioaddr + LPC_WDT_OFF);
+
+	writel(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
+	writel(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
+	writel(1, rtc->ioaddr + LPC_LPA_START_OFF);
+
+	writel(0, rtc->ioaddr + LPC_WDT_OFF);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+}
+
+static irqreturn_t st_rtc_handler(int this_irq, void *data)
+{
+	struct st_rtc *rtc = (struct st_rtc *)data;
+
+	rtc_update_irq(rtc->rtc_dev, 1, RTC_AF);
+
+	return IRQ_HANDLED;
+}
+
+static int st_rtc_read_time(struct device *dev, struct rtc_time *tm)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long lpt_lsb, lpt_msb;
+	unsigned long long lpt;
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	do {
+		lpt_msb = readl(rtc->ioaddr + LPC_LPT_MSB_OFF);
+		lpt_lsb = readl(rtc->ioaddr + LPC_LPT_LSB_OFF);
+	} while (readl(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb;
+	do_div(lpt, rtc->clkrate);
+	rtc_time_to_tm(lpt, tm);
+
+	return 0;
+}
+
+static int st_rtc_set_time(struct device *dev, struct rtc_time *tm)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long long lpt;
+	unsigned long secs, flags;
+	int ret;
+
+	ret = rtc_tm_to_time(tm, &secs);
+	if (ret)
+		return ret;
+
+	lpt = (unsigned long long)secs * rtc->clkrate;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	writel(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF);
+	writel(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF);
+	writel(1, rtc->ioaddr + LPC_LPT_START_OFF);
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	return 0;
+}
+
+static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtc->lock, flags);
+
+	memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm));
+
+	spin_unlock_irqrestore(&rtc->lock, flags);
+
+	return 0;
+}
+
+static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+
+	if (enabled && !rtc->irq_enabled) {
+		enable_irq(rtc->irq);
+		rtc->irq_enabled = true;
+	} else if (!enabled && rtc->irq_enabled) {
+		disable_irq(rtc->irq);
+		rtc->irq_enabled = false;
+	}
+
+	return 0;
+}
+
+static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+	struct rtc_time now;
+	unsigned long now_secs;
+	unsigned long alarm_secs;
+	unsigned long long lpa;
+
+	st_rtc_read_time(dev, &now);
+	rtc_tm_to_time(&now, &now_secs);
+	rtc_tm_to_time(&t->time, &alarm_secs);
+
+	/* Invalid alarm time */
+	if (now_secs > alarm_secs)
+		return -EINVAL;
+
+	memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm));
+
+	/* Now many secs to fire */
+	alarm_secs -= now_secs;
+	lpa = (unsigned long long)alarm_secs * rtc->clkrate;
+
+	st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa);
+	st_rtc_alarm_irq_enable(dev, t->enabled);
+
+	return 0;
+}
+
+static struct rtc_class_ops st_rtc_ops = {
+	.read_time		= st_rtc_read_time,
+	.set_time		= st_rtc_set_time,
+	.read_alarm		= st_rtc_read_alarm,
+	.set_alarm		= st_rtc_set_alarm,
+	.alarm_irq_enable	= st_rtc_alarm_irq_enable,
+};
+
+static int st_rtc_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct st_rtc *rtc;
+	struct resource *res;
+	struct rtc_time tm_check;
+	uint32_t mode;
+	int ret = 0;
+
+	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
+	if (ret) {
+		dev_err(&pdev->dev, "An LPC mode must be provided\n");
+		return -EINVAL;
+	}
+
+	/* LPC can either run in RTC or WDT mode */
+	if (mode != ST_LPC_MODE_RTC)
+		return -ENODEV;
+
+	rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL);
+	if (!rtc)
+		return -ENOMEM;
+
+	spin_lock_init(&rtc->lock);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(rtc->ioaddr))
+		return PTR_ERR(rtc->ioaddr);
+
+	rtc->irq = irq_of_parse_and_map(np, 0);
+	if (!rtc->irq) {
+		dev_err(&pdev->dev, "IRQ missing or invalid\n");
+		return -EINVAL;
+	}
+
+	ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0,
+			       pdev->name, rtc);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq);
+		return ret;
+	}
+
+	enable_irq_wake(rtc->irq);
+	disable_irq(rtc->irq);
+
+	rtc->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rtc->clk)) {
+		dev_err(&pdev->dev, "Unable to request clock\n");
+		return PTR_ERR(rtc->clk);
+	}
+
+	clk_prepare_enable(rtc->clk);
+
+	rtc->clkrate = clk_get_rate(rtc->clk);
+	if (!rtc->clkrate) {
+		dev_err(&pdev->dev, "Unable to fetch clock rate\n");
+		return -EINVAL;
+	}
+
+	device_set_wakeup_capable(&pdev->dev, 1);
+
+	platform_set_drvdata(pdev, rtc);
+
+	/*
+	 * The RTC-LPC is able to manage date.year > 2038
+	 * but currently the kernel can not manage this date!
+	 * If the RTC-LPC has a date.year > 2038 then
+	 * it's set to the epoch "Jan 1st 2000"
+	 */
+	st_rtc_read_time(&pdev->dev, &tm_check);
+
+	if (tm_check.tm_year >=  (2038 - 1900)) {
+		memset(&tm_check, 0, sizeof(tm_check));
+		tm_check.tm_year = 100;
+		tm_check.tm_mday = 1;
+		st_rtc_set_time(&pdev->dev, &tm_check);
+	}
+
+	rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev,
+					   &st_rtc_ops, THIS_MODULE);
+	if (IS_ERR(rtc->rtc_dev)) {
+		clk_disable_unprepare(rtc->clk);
+		return PTR_ERR(rtc->rtc_dev);
+	}
+
+	return 0;
+}
+
+static int st_rtc_remove(struct platform_device *pdev)
+{
+	struct st_rtc *rtc = platform_get_drvdata(pdev);
+
+	if (likely(rtc->rtc_dev))
+		rtc_device_unregister(rtc->rtc_dev);
+
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int st_rtc_suspend(struct device *dev)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		return 0;
+
+	writel(1, rtc->ioaddr + LPC_WDT_OFF);
+	writel(0, rtc->ioaddr + LPC_LPA_START_OFF);
+	writel(0, rtc->ioaddr + LPC_WDT_OFF);
+
+	return 0;
+}
+
+static int st_rtc_resume(struct device *dev)
+{
+	struct st_rtc *rtc = dev_get_drvdata(dev);
+
+	rtc_alarm_irq_enable(rtc->rtc_dev, 0);
+
+	/*
+	 * clean 'rtc->alarm' to allow a new
+	 * .set_alarm to the upper RTC layer
+	 */
+	memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm));
+
+	writel(0, rtc->ioaddr + LPC_LPA_MSB_OFF);
+	writel(0, rtc->ioaddr + LPC_LPA_LSB_OFF);
+	writel(1, rtc->ioaddr + LPC_WDT_OFF);
+	writel(1, rtc->ioaddr + LPC_LPA_START_OFF);
+	writel(0, rtc->ioaddr + LPC_WDT_OFF);
+
+	return 0;
+}
+#endif
+
+static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume);
+
+static struct of_device_id st_rtc_match[] = {
+	{ .compatible = "st,stih407-lpc" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, st_wdog_match);
+
+static struct platform_driver st_rtc_platform_driver = {
+	.driver = {
+		.name = "st-lpc-rtc",
+		.pm = &st_rtc_pm_ops,
+		.of_match_table = st_rtc_match,
+	},
+	.probe = st_rtc_probe,
+	.remove = st_rtc_remove,
+};
+
+module_platform_driver(st_rtc_platform_driver);
+
+MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver");
+MODULE_AUTHOR("David Paris <david.paris@st.com>");
+MODULE_LICENSE("GPLv2");
-- 
1.9.1

[PATCH v3 8/8] MAINTAINERS: Add Watchdog and RTC files to STI's maintainer entry

[Lee Jones]

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 MAINTAINERS | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index ddb9ac8..7060aa6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -1439,10 +1439,12 @@ F:	drivers/phy/phy-stih407-usb.c
 F:	drivers/phy/phy-stih41x-usb.c
 F:	drivers/pinctrl/pinctrl-st.c
 F:	drivers/reset/sti/
+F:	drivers/rtc/rtc-st-lpc.c
 F:	drivers/tty/serial/st-asc.c
 F:	drivers/usb/dwc3/dwc3-st.c
 F:	drivers/usb/host/ehci-st.c
 F:	drivers/usb/host/ohci-st.c
+F:	drivers/watchdog/st_lpc_wdt.c
 F:	drivers/ata/ahci_st.c
 
 ARM/TECHNOLOGIC SYSTEMS TS7250 MACHINE SUPPORT
-- 
1.9.1

Re: [STLinux Kernel] [PATCH v3 7/8] rtc: st: add new driver for ST's LPC RTC

[Peter Griffin]

Hi Lee,

On Wed, 18 Feb 2015, Lee Jones wrote:

> ST's Low Power Controller (LPC) controls two devices; watchdog and RTC.
> Only one of the devices can be used at any one time.  This is enforced
> by the correlating MFD driver.  This portion of the driver-set controls
> the Real Time Clock.

<snip>

> +{
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&rtc->lock, flags);
> +
> +	writel(1, rtc->ioaddr + LPC_WDT_OFF);
> +
> +	writel(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
> +	writel(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
> +	writel(1, rtc->ioaddr + LPC_LPA_START_OFF);
> +
> +	writel(0, rtc->ioaddr + LPC_WDT_OFF);

I think all the writel IO accessors in this driver can be replaced
with the *_relaxed variant. This will avoid the overhead of taking a
spinlock in the l2 outer cache part of writel.

<snip>

> +#ifdef CONFIG_PM_SLEEP
> +static int st_rtc_suspend(struct device *dev)
> +{
> +	struct st_rtc *rtc = dev_get_drvdata(dev);
> +
> +	if (device_may_wakeup(dev))
> +		return 0;
> +
> +	writel(1, rtc->ioaddr + LPC_WDT_OFF);
> +	writel(0, rtc->ioaddr + LPC_LPA_START_OFF);
> +	writel(0, rtc->ioaddr + LPC_WDT_OFF);

Is there a reason for not disabling the IP clock in suspend / resume functions?

regards,

Peter.

Re: [STLinux Kernel] [PATCH v3 5/8] watchdog: st_wdt: Add new driver for ST's LPC Watchdog

[Peter Griffin]

Hi Lee,

<snip>

> +#ifdef CONFIG_PM_SLEEP
> +static int st_wdog_suspend(struct device *dev)
> +{
> +	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
> +
> +	if (watchdog_active(&st_wdog_dev))
> +		st_wdog_stop(&st_wdog_dev);
> +
> +	st_wdog_setup(st_wdog, false);

I was expecting the suspend / resume callbacks would be disabling / enabling
the IP clock.

Is there a reason why it doesn't?

>From looking at the code by this point the watchdog has already been disabled so gating
the IP seems reasonable.

regards,

Peter

Re: [v3,5/8] watchdog: st_wdt: Add new driver for ST's LPC Watchdog

[Guenter Roeck]

On Wed, Feb 18, 2015 at 11:49:11AM +0000, Lee Jones wrote:
> Signed-off-by: David Paris <david.paris@st.com>
> Signed-off-by: Lee Jones <lee.jones@linaro.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Re: [STLinux Kernel] [PATCH v3 7/8] rtc: st: add new driver for ST's LPC RTC

[Lee Jones]

On Mon, 23 Feb 2015, Peter Griffin wrote:
> On Wed, 18 Feb 2015, Lee Jones wrote:
> 
> > ST's Low Power Controller (LPC) controls two devices; watchdog and RTC.
> > Only one of the devices can be used at any one time.  This is enforced
> > by the correlating MFD driver.  This portion of the driver-set controls
> > the Real Time Clock.
> 
> <snip>
> 
> > +{
> > +	unsigned long flags;
> > +
> > +	spin_lock_irqsave(&rtc->lock, flags);
> > +
> > +	writel(1, rtc->ioaddr + LPC_WDT_OFF);
> > +
> > +	writel(msb, rtc->ioaddr + LPC_LPA_MSB_OFF);
> > +	writel(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF);
> > +	writel(1, rtc->ioaddr + LPC_LPA_START_OFF);
> > +
> > +	writel(0, rtc->ioaddr + LPC_WDT_OFF);
> 
> I think all the writel IO accessors in this driver can be replaced
> with the *_relaxed variant. This will avoid the overhead of taking a
> spinlock in the l2 outer cache part of writel.

Yes, there is no technical reason why we can't use the relaxed
variants.  Will fix.

> > +#ifdef CONFIG_PM_SLEEP
> > +static int st_rtc_suspend(struct device *dev)
> > +{
> > +	struct st_rtc *rtc = dev_get_drvdata(dev);
> > +
> > +	if (device_may_wakeup(dev))
> > +		return 0;
> > +
> > +	writel(1, rtc->ioaddr + LPC_WDT_OFF);
> > +	writel(0, rtc->ioaddr + LPC_LPA_START_OFF);
> > +	writel(0, rtc->ioaddr + LPC_WDT_OFF);
> 
> Is there a reason for not disabling the IP clock in suspend / resume functions?

There is.  It will stop the alarm timer, which is undesirable.

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog

Re: [STLinux Kernel] [PATCH v3 7/8] rtc: st: add new driver for ST's LPC RTC

[Russell King - ARM Linux]

On Mon, Feb 23, 2015 at 10:12:23AM +0000, Peter Griffin wrote:
> I think all the writel IO accessors in this driver can be replaced
> with the *_relaxed variant. This will avoid the overhead of taking a
> spinlock in the l2 outer cache part of writel.

You're really operating on old information.  With much improved L2 cache
support code which went in a year or so ago, for the popular L2 cache
controllers, we don't take a spinlock anymore - we just write to the
register directly.

The spinlock is only present for L2C-220 controllers, which are rare.

Moreover, taking the spinlock is only expensive if you have things like
lockdep enabled, otherwise it should be inline and will be fast.

However, using the _relaxed variants where we can get away with weaker
ordering of the writes to the device is a good thing nevertheless.  I'm
just pointing out that your reasoning above is wrong.

-- 
FTTC broadband for 0.8mile line: currently at 10.5Mbps down 400kbps up
according to speedtest.net.

Re: [STLinux Kernel] [PATCH v3 7/8] rtc: st: add new driver for ST's LPC RTC

[Peter Griffin]

Hi Russell,

On Wed, 25 Feb 2015, Russell King - ARM Linux wrote:

> On Mon, Feb 23, 2015 at 10:12:23AM +0000, Peter Griffin wrote:
> > I think all the writel IO accessors in this driver can be replaced
> > with the *_relaxed variant. This will avoid the overhead of taking a
> > spinlock in the l2 outer cache part of writel.
> 
> You're really operating on old information.  With much improved L2 cache
> support code which went in a year or so ago, for the popular L2 cache
> controllers, we don't take a spinlock anymore - we just write to the
> register directly.
> 
> The spinlock is only present for L2C-220 controllers, which are rare.
> 
> Moreover, taking the spinlock is only expensive if you have things like
> lockdep enabled, otherwise it should be inline and will be fast.
> 
> However, using the _relaxed variants where we can get away with weaker
> ordering of the writes to the device is a good thing nevertheless.  I'm
> just pointing out that your reasoning above is wrong.

Thanks for pointing this out, I wasn't aware until now that the spinlock
had been removed.

regards

Peter.

Re: [STLinux Kernel] [PATCH v3 5/8] watchdog: st_wdt: Add new driver for ST's LPC Watchdog

[Peter Griffin]

Hi Lee,

On Mon, 23 Feb 2015, Peter Griffin wrote:

> Hi Lee,

I noticed you sent another version, but I didn't see a reply on this point below.

As your now doing a re-spin for Pauls comments, I thought I would send a reminder
just in case you hadn't seen it.

regards,

Peter.

> 
> <snip>
> 
> > +#ifdef CONFIG_PM_SLEEP
> > +static int st_wdog_suspend(struct device *dev)
> > +{
> > +	struct st_wdog *st_wdog = watchdog_get_drvdata(&st_wdog_dev);
> > +
> > +	if (watchdog_active(&st_wdog_dev))
> > +		st_wdog_stop(&st_wdog_dev);
> > +
> > +	st_wdog_setup(st_wdog, false);
> 
> I was expecting the suspend / resume callbacks would be disabling / enabling
> the IP clock.
> 
> Is there a reason why it doesn't?
> 
> From looking at the code by this point the watchdog has already been disabled so gating
> the IP seems reasonable.
> 
> regards,
> 
> Peter