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.

Changes since v1:
	- Register the gpio_chip in the platform device probe

1. https://lkml.org/lkml/2011/4/19/401

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
Signed-off-by: Jamie Iles <jamie@jamieiles.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

3 files changed, 176 insertions, 148 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 44235bd4f9d..b57ec09af89 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 7b2bdceca08..d92ce3a62ae 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 b2ec45ffe44..8152e9f516b 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 gpiochip_add(&bgc->gc);
+}
+
+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@gmail.com>");