GPIO: MIPS: lantiq: convert gpio-mm-lantiq to OF and of_mm_gpio

Implements OF support and convert to of_mm_gpio.

By attaching hardware latches to the External Bus Unit (EBU) on Lantiq SoC, it
is possible to create output only gpios. This driver configures a special
memory address, which when written to, outputs 16 bit to the latches.

Signed-off-by: John Crispin <blogic@openwrt.org>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Patchwork: https://patchwork.linux-mips.org/patch/3840/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 89 insertions, 57 deletions

diff --git a/drivers/gpio/gpio-mm-lantiq.c b/drivers/gpio/gpio-mm-lantiq.c
index b91c7f17f10f..2983dfbd0668 100644
--- a/drivers/gpio/gpio-mm-lantiq.c
+++ b/drivers/gpio/gpio-mm-lantiq.c
@@ -3,16 +3,19 @@
  *  under the terms of the GNU General Public License version 2 as published
  *  by the Free Software Foundation.
  *
- *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
+ *  Copyright (C) 2012 John Crispin <blogic@openwrt.org>
  */
 
 #include <linux/init.h>
-#include <linux/export.h>
+#include <linux/module.h>
 #include <linux/types.h>
 #include <linux/platform_device.h>
 #include <linux/mutex.h>
 #include <linux/gpio.h>
+#include <linux/of.h>
+#include <linux/of_gpio.h>
 #include <linux/io.h>
+#include <linux/slab.h>
 
 #include <lantiq_soc.h>
 
@@ -25,102 +28,131 @@
 #define LTQ_EBU_BUSCON  0x1e7ff         /* 16 bit access, slowest timing */
 #define LTQ_EBU_WP      0x80000000      /* write protect bit */
 
-/* we keep a shadow value of the last value written to the ebu */
-static int ltq_ebu_gpio_shadow = 0x0;
-static void __iomem *ltq_ebu_gpio_membase;
+struct ltq_mm {
+        struct of_mm_gpio_chip mmchip;
+        u16 shadow;     /* shadow the latches state */
+};
 
-static void ltq_ebu_apply(void)
+/**
+ * ltq_mm_apply() - write the shadow value to the ebu address.
+ * @chip:     Pointer to our private data structure.
+ *
+ * Write the shadow value to the EBU to set the gpios. We need to set the
+ * global EBU lock to make sure that PCI/MTD dont break.
+ */
+static void ltq_mm_apply(struct ltq_mm *chip)
 {
         unsigned long flags;
 
         spin_lock_irqsave(&ebu_lock, flags);
         ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
-        *((__u16 *)ltq_ebu_gpio_membase) = ltq_ebu_gpio_shadow;
+        __raw_writew(chip->shadow, chip->mmchip.regs);
         ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
         spin_unlock_irqrestore(&ebu_lock, flags);
 }
 
-static void ltq_ebu_set(struct gpio_chip *chip, unsigned offset, int value)
+/**
+ * ltq_mm_set() - gpio_chip->set - set gpios.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ * @val:    Value to be written to specified signal.
+ *
+ * Set the shadow value and call ltq_mm_apply.
+ */
+static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
 {
+        struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
+        struct ltq_mm *chip =
+                container_of(mm_gc, struct ltq_mm, mmchip);
+
         if (value)
-                ltq_ebu_gpio_shadow |= (1 << offset);
+                chip->shadow |= (1 << offset);
         else
-                ltq_ebu_gpio_shadow &= ~(1 << offset);
-        ltq_ebu_apply();
+                chip->shadow &= ~(1 << offset);
+        ltq_mm_apply(chip);
 }
 
-static int ltq_ebu_direction_output(struct gpio_chip *chip, unsigned offset,
-        int value)
+/**
+ * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
+ * @gc:     Pointer to gpio_chip device structure.
+ * @gpio:   GPIO signal number.
+ * @val:    Value to be written to specified signal.
+ *
+ * Same as ltq_mm_set, always returns 0.
+ */
+static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
 {
-        ltq_ebu_set(chip, offset, value);
+        ltq_mm_set(gc, offset, value);
 
         return 0;
 }
 
-static struct gpio_chip ltq_ebu_chip = {
-        .label = "ltq_ebu",
-        .direction_output = ltq_ebu_direction_output,
-        .set = ltq_ebu_set,
-        .base = 72,
-        .ngpio = 16,
-        .can_sleep = 1,
-        .owner = THIS_MODULE,
-};
+/**
+ * ltq_mm_save_regs() - Set initial values of GPIO pins
+ * @mm_gc: pointer to memory mapped GPIO chip structure
+ */
+static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
+{
+        struct ltq_mm *chip =
+                container_of(mm_gc, struct ltq_mm, mmchip);
+
+        /* tell the ebu controller which memory address we will be using */
+        ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
+
+        ltq_mm_apply(chip);
+}
 
-static int ltq_ebu_probe(struct platform_device *pdev)
+static int ltq_mm_probe(struct platform_device *pdev)
 {
-        int ret = 0;
         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        struct ltq_mm *chip;
+        const __be32 *shadow;
+        int ret = 0;
 
         if (!res) {
                 dev_err(&pdev->dev, "failed to get memory resource\n");
                 return -ENOENT;
         }
 
-        res = devm_request_mem_region(&pdev->dev, res->start,
-                resource_size(res), dev_name(&pdev->dev));
-        if (!res) {
-                dev_err(&pdev->dev, "failed to request memory resource\n");
-                return -EBUSY;
-        }
-
-        ltq_ebu_gpio_membase = devm_ioremap_nocache(&pdev->dev, res->start,
-                resource_size(res));
-        if (!ltq_ebu_gpio_membase) {
-                dev_err(&pdev->dev, "Failed to ioremap mem region\n");
+        chip = kzalloc(sizeof(*chip), GFP_KERNEL);
+        if (!chip)
                 return -ENOMEM;
-        }
 
-        /* grab the default shadow value passed form the platform code */
-        ltq_ebu_gpio_shadow = (unsigned int) pdev->dev.platform_data;
+        chip->mmchip.gc.ngpio = 16;
+        chip->mmchip.gc.label = "gpio-mm-ltq";
+        chip->mmchip.gc.direction_output = ltq_mm_dir_out;
+        chip->mmchip.gc.set = ltq_mm_set;
+        chip->mmchip.save_regs = ltq_mm_save_regs;
 
-        /* tell the ebu controller which memory address we will be using */
-        ltq_ebu_w32(pdev->resource->start | 0x1, LTQ_EBU_ADDRSEL1);
+        /* store the shadow value if one was passed by the devicetree */
+        shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL);
+        if (shadow)
+                chip->shadow = be32_to_cpu(*shadow);
 
-        /* write protect the region */
-        ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
-
-        ret = gpiochip_add(&ltq_ebu_chip);
-        if (!ret)
-                ltq_ebu_apply();
+        ret = of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip);
+        if (ret)
+                kfree(chip);
         return ret;
 }
 
-static struct platform_driver ltq_ebu_driver = {
-        .probe = ltq_ebu_probe,
+static const struct of_device_id ltq_mm_match[] = {
+        { .compatible = "lantiq,gpio-mm" },
+        {},
+};
+MODULE_DEVICE_TABLE(of, ltq_mm_match);
+
+static struct platform_driver ltq_mm_driver = {
+        .probe = ltq_mm_probe,
         .driver = {
-                .name = "ltq_ebu",
+                .name = "gpio-mm-ltq",
                 .owner = THIS_MODULE,
+                .of_match_table = ltq_mm_match,
         },
 };
 
-static int __init ltq_ebu_init(void)
+static int __init ltq_mm_init(void)
 {
-        int ret = platform_driver_register(&ltq_ebu_driver);
-
-        if (ret)
-                pr_info("ltq_ebu : Error registering platfom driver!");
-        return ret;
+        return platform_driver_register(&ltq_mm_driver);
 }
 
-postcore_initcall(ltq_ebu_init);
+subsys_initcall(ltq_mm_init);