LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Andres Salomon <dilinger@queued.net>
To: Samuel Ortiz <sameo@linux.intel.com>
Cc: linux-kernel@vger.kernel.org,
	Mark Brown <broonie@opensource.wolfsonmicro.com>
Subject: [PATCH 17/19] mfd-core: add refcounting support to mfd_cells
Date: Wed, 2 Feb 2011 20:22:34 -0800	[thread overview]
Message-ID: <20110202202234.37e741f2@queued.net> (raw)
In-Reply-To: <20110202195417.228e2656@queued.net>


This provides convenience functions for sharing of cells across
multiple mfd clients.  Mfd drivers can provide enable/disable hooks
to actually tweak the hardware, and clients can call
mfd_shared_cell_{en,dis}able without having to worry about whether
or not another client happens to have enabled or disabled the
cell/hardware.

Note that this is purely optional; drivers can continue to use
the mfd_cell's enable/disable hooks for their own purposes, if
desired.

Signed-off-by: Andres Salomon <dilinger@queued.net>
---
 drivers/mfd/mfd-core.c   |   51 ++++++++++++++++++++++++++++++++++++++++++---
 include/linux/mfd/core.h |   14 +++++++++++-
 2 files changed, 60 insertions(+), 5 deletions(-)

diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
index d8b9e35..90e9483 100644
--- a/drivers/mfd/mfd-core.c
+++ b/drivers/mfd/mfd-core.c
@@ -18,6 +18,30 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 
+int mfd_shared_cell_enable(struct platform_device *pdev)
+{
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+
+	/* only call enable if the cell hasn't already been enabled */
+	if (atomic_inc_return(cell->usage_count) > 1)
+		return 0;
+
+	return cell->enable(pdev);
+}
+EXPORT_SYMBOL(mfd_shared_cell_enable);
+
+int mfd_shared_cell_disable(struct platform_device *pdev)
+{
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+
+	/* only disable if no other clients are using it */
+	if (atomic_dec_return(cell->usage_count) != 0)
+		return 0;
+
+	return cell->disable(pdev);
+}
+EXPORT_SYMBOL(mfd_shared_cell_disable);
+
 static int mfd_add_device(struct device *parent, int id,
 			  const struct mfd_cell *cell,
 			  struct resource *mem_base,
@@ -97,14 +121,22 @@ fail_alloc:
 }
 
 int mfd_add_devices(struct device *parent, int id,
-		    const struct mfd_cell *cells, int n_devs,
+		    struct mfd_cell *cells, int n_devs,
 		    struct resource *mem_base,
 		    int irq_base)
 {
 	int i;
 	int ret = 0;
+	atomic_t *cnts;
+
+	/* initialize reference counting for all cells */
+	cnts = kcalloc(sizeof(*cnts), n_devs, GFP_KERNEL);
+	if (!cnts)
+		return -ENOMEM;
 
 	for (i = 0; i < n_devs; i++) {
+		atomic_set(&cnts[i], 0);
+		cells[i].usage_count = &cnts[i];
 		ret = mfd_add_device(parent, id, cells + i, mem_base, irq_base);
 		if (ret)
 			break;
@@ -117,15 +149,26 @@ int mfd_add_devices(struct device *parent, int id,
 }
 EXPORT_SYMBOL(mfd_add_devices);
 
-static int mfd_remove_devices_fn(struct device *dev, void *unused)
+static int mfd_remove_devices_fn(struct device *dev, void *c)
 {
-	platform_device_unregister(to_platform_device(dev));
+	struct platform_device *pdev = to_platform_device(dev);
+	const struct mfd_cell *cell = mfd_get_cell(pdev);
+	atomic_t **usage_count = c;
+
+	/* find the lowest address of usage_count pointers (for freeing) */
+	if (!*usage_count || (cell->usage_count < *usage_count))
+		*usage_count = cell->usage_count;
+
+	platform_device_unregister(pdev);
 	return 0;
 }
 
 void mfd_remove_devices(struct device *parent)
 {
-	device_for_each_child(parent, NULL, mfd_remove_devices_fn);
+	atomic_t *cnts = NULL;
+
+	device_for_each_child(parent, &cnts, mfd_remove_devices_fn);
+	kfree(cnts);
 }
 EXPORT_SYMBOL(mfd_remove_devices);
 
diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
index c74089e..d13b992 100644
--- a/include/linux/mfd/core.h
+++ b/include/linux/mfd/core.h
@@ -25,8 +25,11 @@ struct mfd_cell {
 	const char		*name;
 	int			id;
 
+	/* refcounting for multiple drivers to use a single cell */
+	atomic_t		*usage_count;
 	int			(*enable)(struct platform_device *dev);
 	int			(*disable)(struct platform_device *dev);
+
 	int			(*suspend)(struct platform_device *dev);
 	int			(*resume)(struct platform_device *dev);
 
@@ -51,6 +54,15 @@ struct mfd_cell {
 };
 
 /*
+ * Convenience functions for clients using shared cells.  Refcounting
+ * happens automatically, with the cell's enable/disable callbacks
+ * being called only when a device is first being enabled or no other
+ * clients are making use of it.
+ */
+extern int mfd_shared_cell_enable(struct platform_device *pdev);
+extern int mfd_shared_cell_disable(struct platform_device *pdev);
+
+/*
  * Given a platform device that's been created by mfd_add_devices(), fetch
  * the mfd_cell that created it.
  */
@@ -60,7 +72,7 @@ static inline const struct mfd_cell *mfd_get_cell(struct platform_device *pdev)
 }
 
 extern int mfd_add_devices(struct device *parent, int id,
-			   const struct mfd_cell *cells, int n_devs,
+			   struct mfd_cell *cells, int n_devs,
 			   struct resource *mem_base,
 			   int irq_base);
 
-- 
1.7.2.3


  parent reply	other threads:[~2011-02-03  4:22 UTC|newest]

Thread overview: 65+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-03  3:54 [RFC] [PATCH 0/19] mfd sharing support Andres Salomon
2011-02-03  3:55 ` [PATCH 01/19] mfd-core: unconditionally add mfd_cell to every platform_device Andres Salomon
2011-02-03  3:58 ` [PATCH 02/19] jz4740: mfd_cell is now implicitly available to drivers Andres Salomon
2011-02-03  8:09   ` Jean Delvare
2011-02-03  4:01 ` [PATCH 03/19] ab3550: " Andres Salomon
2011-02-04  8:20   ` Mattias Wallin
2011-02-03  4:03 ` [PATCH 04/19] ab3100: " Andres Salomon
2011-02-03 12:52   ` Linus Walleij
2011-02-03  4:04 ` [PATCH 05/19] asic3: " Andres Salomon
2011-02-03  4:05 ` [PATCH 06/19] htc-pasic3: " Andres Salomon
2011-02-03  4:08 ` [PATCH 07/19] timberdale: " Andres Salomon
2011-03-31 23:05   ` Grant Likely
2011-04-01 11:20     ` Samuel Ortiz
2011-04-01 17:47       ` Andres Salomon
2011-04-01 17:56         ` Grant Likely
2011-04-01 18:00           ` Grant Likely
2011-04-01 23:52           ` Samuel Ortiz
2011-04-01 23:58             ` Grant Likely
2011-04-02  0:10               ` Andres Salomon
2011-04-04 10:03               ` Samuel Ortiz
2011-04-05  3:04                 ` Grant Likely
2011-04-06 15:23                   ` Samuel Ortiz
2011-04-06 15:58                     ` Greg KH
2011-04-06 17:05                       ` Samuel Ortiz
2011-04-06 17:16                         ` Ben Hutchings
2011-04-06 17:51                           ` Samuel Ortiz
2011-04-06 18:07                             ` Ben Hutchings
2011-04-06 17:56                         ` Greg KH
2011-04-06 18:25                           ` Andres Salomon
2011-04-06 18:38                             ` Greg KH
2011-04-07  8:04                               ` Grant Likely
2011-04-06 18:47                           ` Samuel Ortiz
2011-04-06 18:59                             ` Felipe Balbi
2011-04-06 22:09                               ` Greg KH
2011-04-07  8:09                                 ` Felipe Balbi
2011-04-07 13:40                               ` Samuel Ortiz
2011-04-07 14:35                                 ` Grant Likely
2011-04-07 15:03                                   ` Samuel Ortiz
2011-04-07 18:06                                     ` Grant Likely
2011-04-07 16:24                   ` Grant Likely
2011-04-01 18:26         ` Samuel Ortiz
2011-02-03  4:09 ` [PATCH 08/19] t7166xb: " Andres Salomon
2011-02-03  4:11 ` [PATCH 09/19] wl1273: " Andres Salomon
2011-02-03  4:12 ` [PATCH 10/19] sh_mobile_sdhi: " Andres Salomon
2011-02-03  4:13 ` [PATCH 11/19] tc6393xb: " Andres Salomon
2011-02-03  4:15 ` [PATCH 12/19] twl4030: " Andres Salomon
2011-02-03  6:05   ` Dmitry Torokhov
2011-02-03  6:39     ` Andres Salomon
2011-02-03  6:53       ` Dmitry Torokhov
2011-02-03  7:03         ` Andres Salomon
2011-02-03  9:31           ` Mark Brown
2011-02-05  2:39             ` Andres Salomon
2011-02-05  3:25               ` Andres Salomon
2011-02-03 12:23           ` Peter Ujfalusi
2011-02-04 10:41           ` Uwe Kleine-König
2011-02-03  4:16 ` [PATCH 13/19] tc6387xb: " Andres Salomon
2011-02-03  4:17 ` [PATCH 14/19] janz: " Andres Salomon
2011-02-03  4:20 ` [PATCH 15/19] mc13xxx: " Andres Salomon
2011-02-04  9:34   ` Uwe Kleine-König
2011-02-04 10:13     ` Uwe Kleine-König
2011-02-04 10:16     ` Andres Salomon
2011-02-03  4:21 ` [PATCH 16/19] mfd-core: drop platform_data/data_size from core mfd_cell struct Andres Salomon
2011-02-03  4:22 ` Andres Salomon [this message]
2011-02-03  4:23 ` [PATCH 18/19] mfd-core: add platform_device sharing support for mfd Andres Salomon
2011-02-03  4:26 ` [PATCH 19/19] cs5535-mfd: add sharing for acpi/pms cells Andres Salomon

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20110202202234.37e741f2@queued.net \
    --to=dilinger@queued.net \
    --cc=broonie@opensource.wolfsonmicro.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=sameo@linux.intel.com \
    --subject='Re: [PATCH 17/19] mfd-core: add refcounting support to mfd_cells' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).