Re: [PATCH v4 5/8] phy: freescale: pcie: Initialize the imx8 pcie standalone phy driver

[Marcel Ziswiler <marcel.ziswiler@toradex.com>]

On Thu, 2021-10-28 at 15:27 +0800, Richard Zhu wrote:
> Add the standalone i.MX8 PCIe PHY driver.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> Tested-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>

Unfortunately, this version no longer works for our IMX8_PCIE_REFCLK_PAD_OUTPUT use-case. Further comments in-
lined below.

> ---
>  drivers/phy/freescale/Kconfig              |   9 +
>  drivers/phy/freescale/Makefile             |   1 +
>  drivers/phy/freescale/phy-fsl-imx8m-pcie.c | 234 +++++++++++++++++++++
>  3 files changed, 244 insertions(+)
>  create mode 100644 drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> 
> diff --git a/drivers/phy/freescale/Kconfig b/drivers/phy/freescale/Kconfig
> index 320630ffe3cd..de9ee7020f76 100644
> --- a/drivers/phy/freescale/Kconfig
> +++ b/drivers/phy/freescale/Kconfig
> @@ -14,3 +14,12 @@ config PHY_MIXEL_MIPI_DPHY
>         help
>           Enable this to add support for the Mixel DSI PHY as found
>           on NXP's i.MX8 family of SOCs.
> +
> +config PHY_FSL_IMX8M_PCIE
> +       tristate "Freescale i.MX8 PCIE PHY"

Above description is missing the M as in i.MX 8M.

> +       depends on OF && HAS_IOMEM
> +       select GENERIC_PHY
> +       default ARCH_MXC && ARM64
> +       help
> +         Enable this to add support for the PCIE PHY as found on
> +         i.MX8M family of SOCs.
> diff --git a/drivers/phy/freescale/Makefile b/drivers/phy/freescale/Makefile
> index 1d02e3869b45..55d07c742ab0 100644
> --- a/drivers/phy/freescale/Makefile
> +++ b/drivers/phy/freescale/Makefile
> @@ -1,3 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  obj-$(CONFIG_PHY_FSL_IMX8MQ_USB)       += phy-fsl-imx8mq-usb.o
>  obj-$(CONFIG_PHY_MIXEL_MIPI_DPHY)      += phy-fsl-imx8-mipi-dphy.o
> +obj-$(CONFIG_PHY_FSL_IMX8M_PCIE)       += phy-fsl-imx8m-pcie.o
> diff --git a/drivers/phy/freescale/phy-fsl-imx8m-pcie.c b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> new file mode 100644
> index 000000000000..4b4402eaddcc
> --- /dev/null
> +++ b/drivers/phy/freescale/phy-fsl-imx8m-pcie.c
> @@ -0,0 +1,234 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright 2021 NXP
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/delay.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/mfd/syscon/imx7-iomuxc-gpr.h>
> +#include <linux/module.h>
> +#include <linux/phy/phy.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/reset.h>
> +#include <dt-bindings/phy/phy-imx8-pcie.h>
> +
> +#define IMX8MM_PCIE_PHY_CMN_REG061     0x184
> +#define  ANA_PLL_CLK_OUT_TO_EXT_IO_EN  BIT(0)
> +#define IMX8MM_PCIE_PHY_CMN_REG062     0x188
> +#define  ANA_PLL_CLK_OUT_TO_EXT_IO_SEL BIT(3)
> +#define IMX8MM_PCIE_PHY_CMN_REG063     0x18C
> +#define  AUX_PLL_REFCLK_SEL_SYS_PLL    GENMASK(7, 6)
> +#define IMX8MM_PCIE_PHY_CMN_REG064     0x190
> +#define  ANA_AUX_RX_TX_SEL_TX          BIT(7)
> +#define  ANA_AUX_RX_TERM_GND_EN                BIT(3)
> +#define  ANA_AUX_TX_TERM               BIT(2)
> +#define IMX8MM_PCIE_PHY_CMN_REG065     0x194
> +#define  ANA_AUX_RX_TERM               (BIT(7) | BIT(4))
> +#define  ANA_AUX_TX_LVL                        GENMASK(3, 0)
> +#define IMX8MM_PCIE_PHY_CMN_REG75      0x1D4
> +#define  PCIE_PHY_CMN_REG75_PLL_DONE   0x3
> +#define PCIE_PHY_TRSV_REG5             0x414
> +#define  PCIE_PHY_TRSV_REG5_GEN1_DEEMP 0x2D
> +#define PCIE_PHY_TRSV_REG6             0x418
> +#define  PCIE_PHY_TRSV_REG6_GEN2_DEEMP 0xF
> +
> +#define IMX8MM_GPR_PCIE_REF_CLK_SEL    GENMASK(25, 24)
> +#define IMX8MM_GPR_PCIE_REF_CLK_PLL    FIELD_PREP(IMX8MM_GPR_PCIE_REF_CLK_SEL, 0x3)
> +#define IMX8MM_GPR_PCIE_REF_CLK_EXT    FIELD_PREP(IMX8MM_GPR_PCIE_REF_CLK_SEL, 0x2)
> +#define IMX8MM_GPR_PCIE_AUX_EN         BIT(19)
> +#define IMX8MM_GPR_PCIE_CMN_RST                BIT(18)
> +#define IMX8MM_GPR_PCIE_POWER_OFF      BIT(17)
> +#define IMX8MM_GPR_PCIE_SSC_EN         BIT(16)
> +#define IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE        BIT(9)
> +
> +struct imx8_pcie_phy {
> +       void __iomem            *base;
> +       struct clk              *clk;
> +       struct phy              *phy;
> +       struct regmap           *iomuxc_gpr;
> +       struct reset_control    *reset;
> +       u32                     refclk_pad_mode;
> +       u32                     tx_deemph_gen1;
> +       u32                     tx_deemph_gen2;
> +       bool                    clkreq_unused;
> +};
> +
> +static int imx8_pcie_phy_init(struct phy *phy)
> +{
> +       int ret;
> +       u32 val, pad_mode;
> +       struct imx8_pcie_phy *imx8_phy = phy_get_drvdata(phy);
> +
> +       reset_control_assert(imx8_phy->reset);
> +
> +       pad_mode = imx8_phy->refclk_pad_mode;
> +       /* Set AUX_EN_OVERRIDE 1'b0, when the CLKREQ# isn't hooked */
> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE,
> +                          imx8_phy->clkreq_unused ?
> +                          0 : IMX8MM_GPR_PCIE_AUX_EN_OVERRIDE);
> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_AUX_EN,
> +                          pad_mode == IMX8_PCIE_REFCLK_PAD_INPUT ?
> +                          IMX8MM_GPR_PCIE_AUX_EN : 0);

V3 had IMX8MM_GPR_PCIE_AUX_EN always enabled. Turns out V4 stopped working for our output use-case as it only
enables it for the input use-case. If I enable this one always it starts working again.

> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_POWER_OFF, 0);
> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_SSC_EN, 0);
> +
> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_REF_CLK_SEL,
> +                          pad_mode == IMX8_PCIE_REFCLK_PAD_INPUT ?
> +                          IMX8MM_GPR_PCIE_REF_CLK_EXT :
> +                          IMX8MM_GPR_PCIE_REF_CLK_PLL);
> +       usleep_range(100, 200);
> +
> +       /* Do the PHY common block reset */
> +       regmap_update_bits(imx8_phy->iomuxc_gpr, IOMUXC_GPR14,
> +                          IMX8MM_GPR_PCIE_CMN_RST,
> +                          IMX8MM_GPR_PCIE_CMN_RST);
> +       usleep_range(200, 500);
> +
> +
> +       if (pad_mode == IMX8_PCIE_REFCLK_PAD_INPUT) {
> +               /* Configure the pad as input */
> +               val = readl(imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> +               writel(val & ~ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> +       } else if (pad_mode == IMX8_PCIE_REFCLK_PAD_OUTPUT) {
> +               /* Configure the PHY to output the refclock via pad */
> +               writel(ANA_PLL_CLK_OUT_TO_EXT_IO_EN,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG061);
> +               writel(ANA_PLL_CLK_OUT_TO_EXT_IO_SEL,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG062);
> +               writel(AUX_PLL_REFCLK_SEL_SYS_PLL,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG063);
> +               val = ANA_AUX_RX_TX_SEL_TX | ANA_AUX_TX_TERM;
> +               writel(val | ANA_AUX_RX_TERM_GND_EN,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG064);
> +               writel(ANA_AUX_RX_TERM | ANA_AUX_TX_LVL,
> +                      imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG065);
> +       }
> +
> +       /* Tune PHY de-emphasis setting to pass PCIe compliance. */
> +       writel(imx8_phy->tx_deemph_gen1, imx8_phy->base + PCIE_PHY_TRSV_REG5);
> +       writel(imx8_phy->tx_deemph_gen2, imx8_phy->base + PCIE_PHY_TRSV_REG6);
> +
> +       reset_control_deassert(imx8_phy->reset);
> +
> +       /* Polling to check the phy is ready or not. */
> +       ret = readl_poll_timeout(imx8_phy->base + IMX8MM_PCIE_PHY_CMN_REG75,
> +                                val, val == PCIE_PHY_CMN_REG75_PLL_DONE,
> +                                10, 20000);
> +       return ret;
> +}
> +
> +static int imx8_pcie_phy_power_on(struct phy *phy)
> +{
> +       struct imx8_pcie_phy *imx8_phy = phy_get_drvdata(phy);
> +
> +       return clk_prepare_enable(imx8_phy->clk);
> +}
> +
> +static int imx8_pcie_phy_power_off(struct phy *phy)
> +{
> +       struct imx8_pcie_phy *imx8_phy = phy_get_drvdata(phy);
> +
> +       clk_disable_unprepare(imx8_phy->clk);
> +
> +       return 0;
> +}
> +
> +static const struct phy_ops imx8_pcie_phy_ops = {
> +       .init           = imx8_pcie_phy_init,
> +       .power_on       = imx8_pcie_phy_power_on,
> +       .power_off      = imx8_pcie_phy_power_off,
> +       .owner          = THIS_MODULE,
> +};
> +
> +static int imx8_pcie_phy_probe(struct platform_device *pdev)
> +{
> +       struct phy_provider *phy_provider;
> +       struct device *dev = &pdev->dev;
> +       struct device_node *np = dev->of_node;
> +       struct imx8_pcie_phy *imx8_phy;
> +       struct resource *res;
> +
> +       imx8_phy = devm_kzalloc(dev, sizeof(*imx8_phy), GFP_KERNEL);
> +       if (!imx8_phy)
> +               return -ENOMEM;
> +
> +       /* get PHY refclk pad mode */
> +       of_property_read_u32(np, "fsl,refclk-pad-mode",
> +                            &imx8_phy->refclk_pad_mode);
> +
> +       if (of_property_read_u32(np, "fsl,tx-deemph-gen1",
> +                                &imx8_phy->tx_deemph_gen1))
> +               imx8_phy->tx_deemph_gen1 = 0;

Is zero here really a sane default or should we rather use the previous hard-coded value?

> +
> +       if (of_property_read_u32(np, "fsl,tx-deemph-gen2",
> +                                &imx8_phy->tx_deemph_gen2))
> +               imx8_phy->tx_deemph_gen2 = 0;

Ditto.

> +
> +       if (of_property_read_bool(np, "fsl,clkreq-unsupported"))
> +               imx8_phy->clkreq_unused = true;
> +       else
> +               imx8_phy->clkreq_unused = false;
> +
> +       imx8_phy->clk = devm_clk_get(dev, "ref");
> +       if (IS_ERR(imx8_phy->clk)) {
> +               dev_err(dev, "failed to get imx pcie phy clock\n");
> +               return PTR_ERR(imx8_phy->clk);
> +       }
> +
> +       /* Grab GPR config register range */
> +       imx8_phy->iomuxc_gpr =
> +                syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
> +       if (IS_ERR(imx8_phy->iomuxc_gpr)) {
> +               dev_err(dev, "unable to find iomuxc registers\n");
> +               return PTR_ERR(imx8_phy->iomuxc_gpr);
> +       }
> +
> +       imx8_phy->reset = devm_reset_control_get_exclusive(dev, "pciephy");
> +       if (IS_ERR(imx8_phy->reset)) {
> +               dev_err(dev, "Failed to get PCIEPHY reset control\n");
> +               return PTR_ERR(imx8_phy->reset);
> +       }
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       imx8_phy->base = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(imx8_phy->base))
> +               return PTR_ERR(imx8_phy->base);
> +
> +       imx8_phy->phy = devm_phy_create(dev, NULL, &imx8_pcie_phy_ops);
> +       if (IS_ERR(imx8_phy->phy))
> +               return PTR_ERR(imx8_phy->phy);
> +
> +       phy_set_drvdata(imx8_phy->phy, imx8_phy);
> +
> +       phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
> +
> +       return PTR_ERR_OR_ZERO(phy_provider);
> +}
> +
> +static const struct of_device_id imx8_pcie_phy_of_match[] = {
> +       {.compatible = "fsl,imx8mm-pcie-phy",},
> +       { },
> +};
> +MODULE_DEVICE_TABLE(of, imx8_pcie_phy_of_match);
> +
> +static struct platform_driver imx8_pcie_phy_driver = {
> +       .probe  = imx8_pcie_phy_probe,
> +       .driver = {
> +               .name   = "imx8-pcie-phy",
> +               .of_match_table = imx8_pcie_phy_of_match,
> +       }
> +};
> +module_platform_driver(imx8_pcie_phy_driver);
> +
> +MODULE_DESCRIPTION("FSL IMX8 PCIE PHY driver");
> +MODULE_LICENSE("GPL");