Message-Id: <1304521657-8527-2-git-send-email-jamie@jamieiles.com>
Date:	Wed,  4 May 2011 16:07:35 +0100
From:	Jamie Iles <jamie@...ieiles.com>
To:	linux-kernel@...r.kernel.org
Cc:	grant.likely@...retlab.ca, cbouatmailru@...il.com,
	linux@....linux.org.uk, tglx@...utronix.de, arnd@...db.de,
	nico@...xnic.net, alan@...rguk.ukuu.org.uk,
	Jamie Iles <jamie@...ieiles.com>
Subject: [RFC PATCH 1/3] basic_mmio_gpio: split into a gpio library and platform device

Allow GPIO_BASIC_MMIO_CORE to be used to provide an accessor library
for implementing GPIO drivers whilst abstracting the register access
detail.  Based on a patch from Anton Vorontsov[1] and adapted to allow
bgpio_chip to be embedded in another structure.

1. https://lkml.org/lkml/2011/4/19/401
---
 drivers/gpio/Kconfig            |    6 +
 drivers/gpio/Makefile           |    1 +
 drivers/gpio/basic_mmio_gpio.c  |  317 +++++++++++++++++++++------------------
 include/linux/basic_mmio_gpio.h |   55 +++++++
 4 files changed, 231 insertions(+), 148 deletions(-)

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index b7fac15..ca16a30 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -70,8 +70,14 @@ config GPIO_MAX730X
 
 comment "Memory mapped GPIO drivers:"
 
+config GPIO_BASIC_MMIO_CORE
+	tristate
+	help
+	  Provides core functionality for basic memory-mapped GPIO controllers.
+
 config GPIO_BASIC_MMIO
 	tristate "Basic memory-mapped GPIO controllers support"
+	select GPIO_BASIC_MMIO_CORE
 	help
 	  Say yes here to support basic memory-mapped GPIO controllers.
 
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index cfbdef1..91a295d 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_GPIOLIB)		+= gpiolib.o
 
 obj-$(CONFIG_GPIO_ADP5520)	+= adp5520-gpio.o
 obj-$(CONFIG_GPIO_ADP5588)	+= adp5588-gpio.o
+obj-$(CONFIG_GPIO_BASIC_MMIO_CORE)	+= basic_mmio_gpio.o
 obj-$(CONFIG_GPIO_BASIC_MMIO)	+= basic_mmio_gpio.o
 obj-$(CONFIG_GPIO_LANGWELL)	+= langwell_gpio.o
 obj-$(CONFIG_GPIO_MAX730X)	+= max730x.o
diff --git a/drivers/gpio/basic_mmio_gpio.c b/drivers/gpio/basic_mmio_gpio.c
index b2ec45f..6b1c6e5 100644
--- a/drivers/gpio/basic_mmio_gpio.c
+++ b/drivers/gpio/basic_mmio_gpio.c
@@ -45,6 +45,7 @@ o        `                     ~~~~\___/~~~~    ` controller in FPGA is ,.`
  */
 
 #include <linux/init.h>
+#include <linux/err.h>
 #include <linux/bug.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
@@ -61,44 +62,6 @@ o        `                     ~~~~\___/~~~~    ` controller in FPGA is ,.`
 #include <linux/mod_devicetable.h>
 #include <linux/basic_mmio_gpio.h>
 
-struct bgpio_chip {
-	struct gpio_chip gc;
-
-	unsigned long (*read_reg)(void __iomem *reg);
-	void (*write_reg)(void __iomem *reg, unsigned long data);
-
-	void __iomem *reg_dat;
-	void __iomem *reg_set;
-	void __iomem *reg_clr;
-	void __iomem *reg_dir;
-
-	/* Number of bits (GPIOs): <register width> * 8. */
-	int bits;
-
-	/*
-	 * Some GPIO controllers work with the big-endian bits notation,
-	 * e.g. in a 8-bits register, GPIO7 is the least significant bit.
-	 */
-	unsigned long (*pin2mask)(struct bgpio_chip *bgc, unsigned int pin);
-
-	/*
-	 * Used to lock bgpio_chip->data. Also, this is needed to keep
-	 * shadowed and real data registers writes together.
-	 */
-	spinlock_t lock;
-
-	/* Shadowed data register to clear/set bits safely. */
-	unsigned long data;
-
-	/* Shadowed direction registers to clear/set direction safely. */
-	unsigned long dir;
-};
-
-static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
-{
-	return container_of(gc, struct bgpio_chip, gc);
-}
-
 static void bgpio_write8(void __iomem *reg, unsigned long data)
 {
 	writeb(data, reg);
@@ -284,20 +247,10 @@ static int bgpio_dir_out_inv(struct gpio_chip *gc, unsigned int gpio, int val)
 	return 0;
 }
 
-static void __iomem *bgpio_request_and_map(struct device *dev,
-					   struct resource *res)
-{
-	if (!devm_request_mem_region(dev, res->start, resource_size(res),
-				     res->name ?: "mmio_gpio"))
-		return NULL;
-
-	return devm_ioremap(dev, res->start, resource_size(res));
-}
-
-static int bgpio_setup_accessors(struct platform_device *pdev,
-				 struct bgpio_chip *bgc)
+static int bgpio_setup_accessors(struct device *dev,
+				 struct bgpio_chip *bgc,
+				 bool be)
 {
-	const struct platform_device_id *platid = platform_get_device_id(pdev);
 
 	switch (bgc->bits) {
 	case 8:
@@ -319,13 +272,11 @@ static int bgpio_setup_accessors(struct platform_device *pdev,
 		break;
 #endif /* BITS_PER_LONG >= 64 */
 	default:
-		dev_err(&pdev->dev, "unsupported data width %u bits\n",
-			bgc->bits);
+		dev_err(dev, "unsupported data width %u bits\n", bgc->bits);
 		return -EINVAL;
 	}
 
-	bgc->pin2mask = strcmp(platid->name, "basic-mmio-gpio-be") ?
-		bgpio_pin2mask : bgpio_pin2mask_be;
+	bgc->pin2mask = be ? bgpio_pin2mask_be : bgpio_pin2mask;
 
 	return 0;
 }
@@ -352,51 +303,22 @@ static int bgpio_setup_accessors(struct platform_device *pdev,
  *	- an input direction register (named "dirin") where a 1 bit indicates
  *	the GPIO is an input.
  */
-static int bgpio_setup_io(struct platform_device *pdev,
-			  struct bgpio_chip *bgc)
+static int bgpio_setup_io(struct bgpio_chip *bgc,
+			  void __iomem *dat,
+			  void __iomem *set,
+			  void __iomem *clr)
 {
-	struct resource *res_set;
-	struct resource *res_clr;
-	struct resource *res_dat;
-	resource_size_t dat_sz;
 
-	res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
-	if (!res_dat)
-		return -EINVAL;
-
-	dat_sz = resource_size(res_dat);
-	if (!is_power_of_2(dat_sz))
-		return -EINVAL;
-
-	bgc->bits = dat_sz * 8;
-	if (bgc->bits > BITS_PER_LONG)
-		return -EINVAL;
-
-	bgc->reg_dat = bgpio_request_and_map(&pdev->dev, res_dat);
+	bgc->reg_dat = dat;
 	if (!bgc->reg_dat)
-		return -ENOMEM;
-
-	res_set = platform_get_resource_byname(pdev, IORESOURCE_MEM, "set");
-	res_clr = platform_get_resource_byname(pdev, IORESOURCE_MEM, "clr");
-	if (res_set && res_clr) {
-		if (resource_size(res_set) != resource_size(res_clr) ||
-		    resource_size(res_set) != resource_size(res_dat))
-			return -EINVAL;
-
-		bgc->reg_set = bgpio_request_and_map(&pdev->dev, res_set);
-		bgc->reg_clr = bgpio_request_and_map(&pdev->dev, res_clr);
-		if (!bgc->reg_set || !bgc->reg_clr)
-			return -ENOMEM;
+		return -EINVAL;
 
+	if (set && clr) {
+		bgc->reg_set = set;
+		bgc->reg_clr = clr;
 		bgc->gc.set = bgpio_set_with_clear;
-	} else if (res_set && !res_clr) {
-		if (resource_size(res_set) != resource_size(res_dat))
-			return -EINVAL;
-
-		bgc->reg_set = bgpio_request_and_map(&pdev->dev, res_set);
-		if (!bgc->reg_set)
-			return -ENOMEM;
-
+	} else if (set && !clr) {
+		bgc->reg_set = set;
 		bgc->gc.set = bgpio_set_set;
 	} else {
 		bgc->gc.set = bgpio_set;
@@ -407,27 +329,18 @@ static int bgpio_setup_io(struct platform_device *pdev,
 	return 0;
 }
 
-static int bgpio_setup_direction(struct platform_device *pdev,
-				 struct bgpio_chip *bgc)
+static int bgpio_setup_direction(struct bgpio_chip *bgc,
+				 void __iomem *dirout,
+				 void __iomem *dirin)
 {
-	struct resource *res_dirout;
-	struct resource *res_dirin;
-
-	res_dirout = platform_get_resource_byname(pdev, IORESOURCE_MEM,
-						  "dirout");
-	res_dirin = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dirin");
-	if (res_dirout && res_dirin) {
+	if (dirout && dirin) {
 		return -EINVAL;
-	} else if (res_dirout) {
-		bgc->reg_dir = bgpio_request_and_map(&pdev->dev, res_dirout);
-		if (!bgc->reg_dir)
-			return -ENOMEM;
+	} else if (dirout) {
+		bgc->reg_dir = dirout;
 		bgc->gc.direction_output = bgpio_dir_out;
 		bgc->gc.direction_input = bgpio_dir_in;
-	} else if (res_dirin) {
-		bgc->reg_dir = bgpio_request_and_map(&pdev->dev, res_dirin);
-		if (!bgc->reg_dir)
-			return -ENOMEM;
+	} else if (dirin) {
+		bgc->reg_dir = dirin;
 		bgc->gc.direction_output = bgpio_dir_out_inv;
 		bgc->gc.direction_input = bgpio_dir_in_inv;
 	} else {
@@ -438,60 +351,166 @@ static int bgpio_setup_direction(struct platform_device *pdev,
 	return 0;
 }
 
-static int __devinit bgpio_probe(struct platform_device *pdev)
+int __devexit bgpio_remove(struct bgpio_chip *bgc)
+{
+	int err = gpiochip_remove(&bgc->gc);
+
+	kfree(bgc);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(bgpio_remove);
+
+int __devinit bgpio_init(struct bgpio_chip *bgc,
+			 struct device *dev,
+			 unsigned long sz,
+			 void __iomem *dat,
+			 void __iomem *set,
+			 void __iomem *clr,
+			 void __iomem *dirout,
+			 void __iomem *dirin,
+			 bool big_endian)
 {
-	struct device *dev = &pdev->dev;
-	struct bgpio_pdata *pdata = dev_get_platdata(dev);
-	struct bgpio_chip *bgc;
 	int ret;
-	int ngpio;
 
-	bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
-	if (!bgc)
-		return -ENOMEM;
+	if (!is_power_of_2(sz))
+		return -EINVAL;
 
-	ret = bgpio_setup_io(pdev, bgc);
+	bgc->bits = sz * 8;
+	if (bgc->bits > BITS_PER_LONG)
+		return -EINVAL;
+
+	spin_lock_init(&bgc->lock);
+	bgc->gc.dev = dev;
+	bgc->gc.label = dev_name(dev);
+	bgc->gc.base = -1;
+	bgc->gc.ngpio = bgc->bits;
+
+	ret = bgpio_setup_io(bgc, dat, set, clr);
 	if (ret)
 		return ret;
 
-	ngpio = bgc->bits;
-	if (pdata) {
-		bgc->gc.base = pdata->base;
-		if (pdata->ngpio > 0)
-			ngpio = pdata->ngpio;
-	} else {
-		bgc->gc.base = -1;
-	}
-
-	ret = bgpio_setup_accessors(pdev, bgc);
+	ret = bgpio_setup_accessors(dev, bgc, big_endian);
 	if (ret)
 		return ret;
 
-	spin_lock_init(&bgc->lock);
-	ret = bgpio_setup_direction(pdev, bgc);
+	ret = bgpio_setup_direction(bgc, dirout, dirin);
 	if (ret)
 		return ret;
 
 	bgc->data = bgc->read_reg(bgc->reg_dat);
 
-	bgc->gc.ngpio = ngpio;
-	bgc->gc.dev = dev;
-	bgc->gc.label = dev_name(dev);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(bgpio_init);
 
-	platform_set_drvdata(pdev, bgc);
+#ifdef CONFIG_GPIO_BASIC_MMIO
 
-	ret = gpiochip_add(&bgc->gc);
-	if (ret)
-		dev_err(dev, "gpiochip_add() failed: %d\n", ret);
+static void __iomem *bgpio_map(struct platform_device *pdev,
+			       const char *name,
+			       resource_size_t sane_sz,
+			       int *err)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *r;
+	resource_size_t start;
+	resource_size_t sz;
+	void __iomem *ret;
+
+	*err = 0;
+
+	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, name);
+	if (!r)
+		return NULL;
+
+	sz = resource_size(r);
+	if (sz != sane_sz) {
+		*err = -EINVAL;
+		return NULL;
+	}
+
+	start = r->start;
+	if (!devm_request_mem_region(dev, start, sz, r->name)) {
+		*err = -EBUSY;
+		return NULL;
+	}
+
+	ret = devm_ioremap(dev, start, sz);
+	if (!ret) {
+		*err = -ENOMEM;
+		return NULL;
+	}
 
 	return ret;
 }
 
-static int __devexit bgpio_remove(struct platform_device *pdev)
+static int __devinit bgpio_pdev_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct resource *r;
+	void __iomem *dat;
+	void __iomem *set;
+	void __iomem *clr;
+	void __iomem *dirout;
+	void __iomem *dirin;
+	unsigned long sz;
+	bool be;
+	int err;
+	struct bgpio_chip *bgc;
+	struct bgpio_pdata *pdata = dev_get_platdata(dev);
+
+	r = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
+	if (!r)
+		return -EINVAL;
+
+	sz = resource_size(r);
+
+	dat = bgpio_map(pdev, "dat", sz, &err);
+	if (!dat)
+		return err ? err : -EINVAL;
+
+	set = bgpio_map(pdev, "set", sz, &err);
+	if (err)
+		return err;
+
+	clr = bgpio_map(pdev, "clr", sz, &err);
+	if (err)
+		return err;
+
+	dirout = bgpio_map(pdev, "dirout", sz, &err);
+	if (err)
+		return err;
+
+	dirin = bgpio_map(pdev, "dirin", sz, &err);
+	if (err)
+		return err;
+
+	be = !strcmp(platform_get_device_id(pdev)->name, "basic-mmio-gpio-be");
+
+	bgc = devm_kzalloc(&pdev->dev, sizeof(*bgc), GFP_KERNEL);
+	if (!bgc)
+		return -ENOMEM;
+
+	err = bgpio_init(bgc, dev, sz, dat, set, clr, dirout, dirin, be);
+	if (err)
+		return err;
+
+	if (pdata) {
+		bgc->gc.base = pdata->base;
+		if (pdata->ngpio > 0)
+			bgc->gc.ngpio = pdata->ngpio;
+	}
+
+	platform_set_drvdata(pdev, bgc);
+
+	return 0;
+}
+
+static int __devexit bgpio_pdev_remove(struct platform_device *pdev)
 {
 	struct bgpio_chip *bgc = platform_get_drvdata(pdev);
 
-	return gpiochip_remove(&bgc->gc);
+	return bgpio_remove(bgc);
 }
 
 static const struct platform_device_id bgpio_id_table[] = {
@@ -506,21 +525,23 @@ static struct platform_driver bgpio_driver = {
 		.name = "basic-mmio-gpio",
 	},
 	.id_table = bgpio_id_table,
-	.probe = bgpio_probe,
-	.remove = __devexit_p(bgpio_remove),
+	.probe = bgpio_pdev_probe,
+	.remove = __devexit_p(bgpio_pdev_remove),
 };
 
-static int __init bgpio_init(void)
+static int __init bgpio_platform_init(void)
 {
 	return platform_driver_register(&bgpio_driver);
 }
-module_init(bgpio_init);
+module_init(bgpio_platform_init);
 
-static void __exit bgpio_exit(void)
+static void __exit bgpio_platform_exit(void)
 {
 	platform_driver_unregister(&bgpio_driver);
 }
-module_exit(bgpio_exit);
+module_exit(bgpio_platform_exit);
+
+#endif /* CONFIG_GPIO_BASIC_MMIO */
 
 MODULE_DESCRIPTION("Driver for basic memory-mapped GPIO controllers");
 MODULE_AUTHOR("Anton Vorontsov <cbouatmailru@...il.com>");
diff --git a/include/linux/basic_mmio_gpio.h b/include/linux/basic_mmio_gpio.h
index f23ec73..1ae1271 100644
--- a/include/linux/basic_mmio_gpio.h
+++ b/include/linux/basic_mmio_gpio.h
@@ -13,9 +13,64 @@
 #ifndef __BASIC_MMIO_GPIO_H
 #define __BASIC_MMIO_GPIO_H
 
+#include <linux/gpio.h>
+#include <linux/types.h>
+#include <linux/compiler.h>
+
 struct bgpio_pdata {
 	int base;
 	int ngpio;
 };
 
+struct device;
+
+struct bgpio_chip {
+	struct gpio_chip gc;
+
+	unsigned long (*read_reg)(void __iomem *reg);
+	void (*write_reg)(void __iomem *reg, unsigned long data);
+
+	void __iomem *reg_dat;
+	void __iomem *reg_set;
+	void __iomem *reg_clr;
+	void __iomem *reg_dir;
+
+	/* Number of bits (GPIOs): <register width> * 8. */
+	int bits;
+
+	/*
+	 * Some GPIO controllers work with the big-endian bits notation,
+	 * e.g. in a 8-bits register, GPIO7 is the least significant bit.
+	 */
+	unsigned long (*pin2mask)(struct bgpio_chip *bgc, unsigned int pin);
+
+	/*
+	 * Used to lock bgpio_chip->data. Also, this is needed to keep
+	 * shadowed and real data registers writes together.
+	 */
+	spinlock_t lock;
+
+	/* Shadowed data register to clear/set bits safely. */
+	unsigned long data;
+
+	/* Shadowed direction registers to clear/set direction safely. */
+	unsigned long dir;
+};
+
+static inline struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
+{
+	return container_of(gc, struct bgpio_chip, gc);
+}
+
+int __devexit bgpio_remove(struct bgpio_chip *bgc);
+int __devinit bgpio_init(struct bgpio_chip *bgc,
+			 struct device *dev,
+			 unsigned long sz,
+			 void __iomem *dat,
+			 void __iomem *set,
+			 void __iomem *clr,
+			 void __iomem *dirout,
+			 void __iomem *dirin,
+			 bool big_endian);
+
 #endif /* __BASIC_MMIO_GPIO_H */
-- 
1.7.4.4

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