gpio: Kontron PLD gpio driver

Add gpio support for the on-board PLD found on some Kontron embedded modules.

Originally-from: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Kevin Strasser <kevin.strasser@linux.intel.com>
Acked-by: Darren Hart <dvhart@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

3 files changed, 238 insertions, 0 deletions

diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index 02db4eafa9df..4b7ba53e96db 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -691,6 +691,18 @@ config GPIO_UCB1400
           This enables support for the Philips UCB1400 GPIO pins.
           The UCB1400 is an AC97 audio codec.
 
+comment "LPC GPIO expanders:"
+
+config GPIO_KEMPLD
+        tristate "Kontron ETX / COMexpress GPIO"
+        depends on MFD_KEMPLD
+        help
+          This enables support for the PLD GPIO interface on some Kontron ETX
+          and COMexpress (ETXexpress) modules.
+
+          This driver can also be built as a module. If so, the module will be
+          called gpio-kempld.
+
 comment "MODULbus GPIO expanders:"
 
 config GPIO_JANZ_TTL
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index fa97bf8698ed..156fd283945c 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -29,6 +29,7 @@ obj-$(CONFIG_GPIO_GRGPIO)	+= gpio-grgpio.o
 obj-$(CONFIG_GPIO_ICH)          += gpio-ich.o
 obj-$(CONFIG_GPIO_IT8761E)      += gpio-it8761e.o
 obj-$(CONFIG_GPIO_JANZ_TTL)     += gpio-janz-ttl.o
+obj-$(CONFIG_GPIO_KEMPLD)       += gpio-kempld.o
 obj-$(CONFIG_ARCH_KS8695)       += gpio-ks8695.o
 obj-$(CONFIG_GPIO_LANGWELL)     += gpio-langwell.o
 obj-$(CONFIG_ARCH_LPC32XX)      += gpio-lpc32xx.o
diff --git a/drivers/gpio/gpio-kempld.c b/drivers/gpio/gpio-kempld.c
new file mode 100644
index 000000000000..1bdc3a2e40dc
--- /dev/null
+++ b/drivers/gpio/gpio-kempld.c
@@ -0,0 +1,225 @@
+/*
+ * Kontron PLD GPIO driver
+ *
+ * Copyright (c) 2010-2013 Kontron Europe GmbH
+ * Author: Michael Brunner <michael.brunner@kontron.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License 2 as published
+ * by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/platform_device.h>
+#include <linux/gpio.h>
+#include <linux/mfd/kempld.h>
+
+#define KEMPLD_GPIO_MAX_NUM             16
+#define KEMPLD_GPIO_MASK(x)             (1 << ((x) % 8))
+#define KEMPLD_GPIO_DIR_NUM(x)          (0x40 + (x) / 8)
+#define KEMPLD_GPIO_LVL_NUM(x)          (0x42 + (x) / 8)
+#define KEMPLD_GPIO_EVT_LVL_EDGE        0x46
+#define KEMPLD_GPIO_IEN                 0x4A
+
+struct kempld_gpio_data {
+        struct gpio_chip                chip;
+        struct kempld_device_data       *pld;
+};
+
+/*
+ * Set or clear GPIO bit
+ * kempld_get_mutex must be called prior to calling this function.
+ */
+static void kempld_gpio_bitop(struct kempld_device_data *pld,
+                              u8 reg, u8 bit, u8 val)
+{
+        u8 status;
+
+        status = kempld_read8(pld, reg);
+        if (val)
+                status |= (1 << bit);
+        else
+                status &= ~(1 << bit);
+        kempld_write8(pld, reg, status);
+}
+
+static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
+{
+        u8 status;
+
+        kempld_get_mutex(pld);
+        status = kempld_read8(pld, reg);
+        kempld_release_mutex(pld);
+
+        return !!(status & (1 << bit));
+}
+
+static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
+{
+        struct kempld_gpio_data *gpio
+                = container_of(chip, struct kempld_gpio_data, chip);
+        struct kempld_device_data *pld = gpio->pld;
+
+        return kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset),
+                                   KEMPLD_GPIO_MASK(offset));
+}
+
+static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
+{
+        struct kempld_gpio_data *gpio
+                = container_of(chip, struct kempld_gpio_data, chip);
+        struct kempld_device_data *pld = gpio->pld;
+
+        kempld_get_mutex(pld);
+        kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset),
+                          KEMPLD_GPIO_MASK(offset), value);
+        kempld_release_mutex(pld);
+}
+
+static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
+{
+        struct kempld_gpio_data *gpio
+                = container_of(chip, struct kempld_gpio_data, chip);
+        struct kempld_device_data *pld = gpio->pld;
+
+        kempld_get_mutex(pld);
+        kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset),
+                          KEMPLD_GPIO_MASK(offset), 0);
+        kempld_release_mutex(pld);
+
+        return 0;
+}
+
+static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
+                                        int value)
+{
+        struct kempld_gpio_data *gpio
+                = container_of(chip, struct kempld_gpio_data, chip);
+        struct kempld_device_data *pld = gpio->pld;
+
+        kempld_get_mutex(pld);
+        kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset),
+                          KEMPLD_GPIO_MASK(offset), value);
+        kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset),
+                          KEMPLD_GPIO_MASK(offset), 1);
+        kempld_release_mutex(pld);
+
+        return 0;
+}
+
+static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
+{
+        struct kempld_gpio_data *gpio
+                = container_of(chip, struct kempld_gpio_data, chip);
+        struct kempld_device_data *pld = gpio->pld;
+
+        return kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset),
+                                   KEMPLD_GPIO_MASK(offset));
+}
+
+static int kempld_gpio_pincount(struct kempld_device_data *pld)
+{
+        u16 evt, evt_back;
+
+        kempld_get_mutex(pld);
+
+        /* Backup event register as it might be already initialized */
+        evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
+        /* Clear event register */
+        kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
+        /* Read back event register */
+        evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
+        /* Restore event register */
+        kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
+
+        kempld_release_mutex(pld);
+
+        return evt ? __ffs(evt) : 16;
+}
+
+static int kempld_gpio_probe(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+        struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
+        struct kempld_platform_data *pdata = pld->dev->platform_data;
+        struct kempld_gpio_data *gpio;
+        struct gpio_chip *chip;
+        int ret;
+
+        if (pld->info.spec_major < 2) {
+                dev_err(dev,
+                        "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
+                return -ENODEV;
+        }
+
+        gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
+        if (gpio == NULL)
+                return -ENOMEM;
+
+        gpio->pld = pld;
+
+        platform_set_drvdata(pdev, gpio);
+
+        chip = &gpio->chip;
+        chip->label = "gpio-kempld";
+        chip->owner = THIS_MODULE;
+        chip->dev = dev;
+        chip->can_sleep = 1;
+        if (pdata && pdata->gpio_base)
+                chip->base = pdata->gpio_base;
+        else
+                chip->base = -1;
+        chip->direction_input = kempld_gpio_direction_input;
+        chip->direction_output = kempld_gpio_direction_output;
+        chip->get_direction = kempld_gpio_get_direction;
+        chip->get = kempld_gpio_get;
+        chip->set = kempld_gpio_set;
+        chip->ngpio = kempld_gpio_pincount(pld);
+        if (chip->ngpio == 0) {
+                dev_err(dev, "No GPIO pins detected\n");
+                return -ENODEV;
+        }
+
+        ret = gpiochip_add(chip);
+        if (ret) {
+                dev_err(dev, "Could not register GPIO chip\n");
+                return ret;
+        }
+
+        dev_info(dev, "GPIO functionality initialized with %d pins\n",
+                 chip->ngpio);
+
+        return 0;
+}
+
+static int kempld_gpio_remove(struct platform_device *pdev)
+{
+        struct kempld_gpio_data *gpio = platform_get_drvdata(pdev);
+
+        return gpiochip_remove(&gpio->chip);
+}
+
+static struct platform_driver kempld_gpio_driver = {
+        .driver = {
+                .name = "gpio-kempld",
+                .owner = THIS_MODULE,
+        },
+        .probe          = kempld_gpio_probe,
+        .remove         = kempld_gpio_remove,
+};
+
+module_platform_driver(kempld_gpio_driver);
+
+MODULE_DESCRIPTION("KEM PLD GPIO Driver");
+MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gpio-kempld");