gpio: add driver for MEN 16Z127 GPIO controller

The 16Z127 is a 32bit GPIO controller on a MCB FPGA.
Every single line can be configured as input and output.

Push pull and open drain are supported as well as setting
a debounce value for the input lines.

Signed-off-by: Andreas Werner <andy@wernerandy.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 200 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-menz127.c b/drivers/gpio/gpio-menz127.c
new file mode 100644
index 000000000000..a68e199d579d
--- /dev/null
+++ b/drivers/gpio/gpio-menz127.c
@@ -0,0 +1,200 @@
+/*
+ * MEN 16Z127 GPIO driver
+ *
+ * Copyright (C) 2016 MEN Mikroelektronik GmbH (www.men.de)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; version 2 of the License.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/err.h>
+#include <linux/mcb.h>
+#include <linux/bitops.h>
+#include <linux/gpio/driver.h>
+
+#define MEN_Z127_CTRL   0x00
+#define MEN_Z127_PSR    0x04
+#define MEN_Z127_IRQR   0x08
+#define MEN_Z127_GPIODR 0x0c
+#define MEN_Z127_IER1   0x10
+#define MEN_Z127_IER2   0x14
+#define MEN_Z127_DBER   0x18
+#define MEN_Z127_ODER   0x1C
+#define GPIO_TO_DBCNT_REG(gpio) ((gpio * 4) + 0x80)
+
+#define MEN_Z127_DB_MIN_US      50
+/* 16 bit compare register. Each bit represents 50us */
+#define MEN_Z127_DB_MAX_US      (0xffff * MEN_Z127_DB_MIN_US)
+#define MEN_Z127_DB_IN_RANGE(db)        ((db >= MEN_Z127_DB_MIN_US) && \
+                                         (db <= MEN_Z127_DB_MAX_US))
+
+struct men_z127_gpio {
+        struct gpio_chip gc;
+        void __iomem *reg_base;
+        struct mcb_device *mdev;
+        struct resource *mem;
+        spinlock_t lock;
+};
+
+static int men_z127_debounce(struct gpio_chip *gc, unsigned gpio,
+                             unsigned debounce)
+{
+        struct men_z127_gpio *priv = gpiochip_get_data(gc);
+        struct device *dev = &priv->mdev->dev;
+        unsigned int rnd;
+        u32 db_en, db_cnt;
+
+        if (!MEN_Z127_DB_IN_RANGE(debounce)) {
+                dev_err(dev, "debounce value %u out of range", debounce);
+                return -EINVAL;
+        }
+
+        if (debounce > 0) {
+                /* round up or down depending on MSB-1 */
+                rnd = fls(debounce) - 1;
+
+                if (rnd && (debounce & BIT(rnd - 1)))
+                        debounce = round_up(debounce, MEN_Z127_DB_MIN_US);
+                else
+                        debounce = round_down(debounce, MEN_Z127_DB_MIN_US);
+
+                if (debounce > MEN_Z127_DB_MAX_US)
+                        debounce = MEN_Z127_DB_MAX_US;
+
+                /* 50us per register unit */
+                debounce /= 50;
+        }
+
+        spin_lock(&priv->lock);
+
+        db_en = readl(priv->reg_base + MEN_Z127_DBER);
+
+        if (debounce == 0) {
+                db_en &= ~BIT(gpio);
+                db_cnt = 0;
+        } else {
+                db_en |= BIT(gpio);
+                db_cnt = debounce;
+        }
+
+        writel(db_en, priv->reg_base + MEN_Z127_DBER);
+        writel(db_cnt, priv->reg_base + GPIO_TO_DBCNT_REG(gpio));
+
+        spin_unlock(&priv->lock);
+
+        return 0;
+}
+
+static int men_z127_request(struct gpio_chip *gc, unsigned gpio_pin)
+{
+        struct men_z127_gpio *priv = gpiochip_get_data(gc);
+        u32 od_en;
+
+        if (gpio_pin >= gc->ngpio)
+                return -EINVAL;
+
+        spin_lock(&priv->lock);
+        od_en = readl(priv->reg_base + MEN_Z127_ODER);
+
+        if (gpiochip_line_is_open_drain(gc, gpio_pin))
+                od_en |= BIT(gpio_pin);
+        else
+                od_en &= ~BIT(gpio_pin);
+
+        writel(od_en, priv->reg_base + MEN_Z127_ODER);
+        spin_unlock(&priv->lock);
+
+        return 0;
+}
+
+static int men_z127_probe(struct mcb_device *mdev,
+                          const struct mcb_device_id *id)
+{
+        struct men_z127_gpio *men_z127_gpio;
+        struct device *dev = &mdev->dev;
+        int ret;
+
+        men_z127_gpio = devm_kzalloc(dev, sizeof(struct men_z127_gpio),
+                                     GFP_KERNEL);
+        if (!men_z127_gpio)
+                return -ENOMEM;
+
+        men_z127_gpio->mem = mcb_request_mem(mdev, dev_name(dev));
+        if (IS_ERR(men_z127_gpio->mem)) {
+                dev_err(dev, "failed to request device memory");
+                return PTR_ERR(men_z127_gpio->mem);
+        }
+
+        men_z127_gpio->reg_base = ioremap(men_z127_gpio->mem->start,
+                                          resource_size(men_z127_gpio->mem));
+        if (men_z127_gpio->reg_base == NULL) {
+                ret = -ENXIO;
+                goto err_release;
+        }
+
+        men_z127_gpio->mdev = mdev;
+        mcb_set_drvdata(mdev, men_z127_gpio);
+
+        ret = bgpio_init(&men_z127_gpio->gc, &mdev->dev, 4,
+                         men_z127_gpio->reg_base + MEN_Z127_PSR,
+                         men_z127_gpio->reg_base + MEN_Z127_CTRL,
+                         NULL,
+                         men_z127_gpio->reg_base + MEN_Z127_GPIODR,
+                         NULL, 0);
+        if (ret)
+                goto err_unmap;
+
+        men_z127_gpio->gc.set_debounce = men_z127_debounce;
+        men_z127_gpio->gc.request = men_z127_request;
+
+        ret = gpiochip_add_data(&men_z127_gpio->gc, men_z127_gpio);
+        if (ret) {
+                dev_err(dev, "failed to register MEN 16Z127 GPIO controller");
+                goto err_unmap;
+        }
+
+        dev_info(dev, "MEN 16Z127 GPIO driver registered");
+
+        return 0;
+
+err_unmap:
+        iounmap(men_z127_gpio->reg_base);
+err_release:
+        mcb_release_mem(men_z127_gpio->mem);
+        return ret;
+}
+
+static void men_z127_remove(struct mcb_device *mdev)
+{
+        struct men_z127_gpio *men_z127_gpio = mcb_get_drvdata(mdev);
+
+        gpiochip_remove(&men_z127_gpio->gc);
+        iounmap(men_z127_gpio->reg_base);
+        mcb_release_mem(men_z127_gpio->mem);
+}
+
+static const struct mcb_device_id men_z127_ids[] = {
+        { .device = 0x7f },
+        { }
+};
+MODULE_DEVICE_TABLE(mcb, men_z127_ids);
+
+static struct mcb_driver men_z127_driver = {
+        .driver = {
+                .name = "z127-gpio",
+                .owner = THIS_MODULE,
+        },
+        .probe = men_z127_probe,
+        .remove = men_z127_remove,
+        .id_table = men_z127_ids,
+};
+module_mcb_driver(men_z127_driver);
+
+MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
+MODULE_DESCRIPTION("MEN 16z127 GPIO Controller");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("mcb:16z127");