gpio: add Technologic I2C-FPGA gpio support

This driver is generic and aims to support all Technologic Systems's
boards embedding FPGA GPIOs with an I2C interface.

This driver supports TS-4900, TS-7970, TS-7990 and TS-4100 series.

Signed-off-by: Lucile Quirion <lucile.quirion@savoirfairelinux.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 190 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-ts4900.c b/drivers/gpio/gpio-ts4900.c
new file mode 100644
index 000000000000..9dd9aca820e7
--- /dev/null
+++ b/drivers/gpio/gpio-ts4900.c
@@ -0,0 +1,190 @@
+/*
+ * Digital I/O driver for Technologic Systems I2C FPGA Core
+ *
+ * Copyright (C) 2015 Technologic Systems
+ * Copyright (C) 2016 Savoir-Faire Linux
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether expressed or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License version 2 for more details.
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/of_device.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+
+#define DEFAULT_PIN_NUMBER      32
+/*
+ * Register bits used by the GPIO device
+ * Some boards, such as TS-7970 do not have a separate input bit
+ */
+#define TS4900_GPIO_OE          0x01
+#define TS4900_GPIO_OUT         0x02
+#define TS4900_GPIO_IN          0x04
+#define TS7970_GPIO_IN          0x02
+
+struct ts4900_gpio_priv {
+        struct regmap *regmap;
+        struct gpio_chip gpio_chip;
+        unsigned int input_bit;
+};
+
+static int ts4900_gpio_get_direction(struct gpio_chip *chip,
+                                     unsigned int offset)
+{
+        struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+        unsigned int reg;
+
+        regmap_read(priv->regmap, offset, &reg);
+
+        return !(reg & TS4900_GPIO_OE);
+}
+
+static int ts4900_gpio_direction_input(struct gpio_chip *chip,
+                                       unsigned int offset)
+{
+        struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+
+        /*
+         * This will clear the output enable bit, the other bits are
+         * dontcare when this is cleared
+         */
+        return regmap_write(priv->regmap, offset, 0);
+}
+
+static int ts4900_gpio_direction_output(struct gpio_chip *chip,
+                                        unsigned int offset, int value)
+{
+        struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+        int ret;
+
+        if (value)
+                ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE |
+                                                         TS4900_GPIO_OUT);
+        else
+                ret = regmap_write(priv->regmap, offset, TS4900_GPIO_OE);
+
+        return ret;
+}
+
+static int ts4900_gpio_get(struct gpio_chip *chip, unsigned int offset)
+{
+        struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+        unsigned int reg;
+
+        regmap_read(priv->regmap, offset, &reg);
+
+        return !!(reg & priv->input_bit);
+}
+
+static void ts4900_gpio_set(struct gpio_chip *chip, unsigned int offset,
+                            int value)
+{
+        struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+
+        if (value)
+                regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT,
+                                   TS4900_GPIO_OUT);
+        else
+                regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OUT, 0);
+}
+
+static const struct regmap_config ts4900_regmap_config = {
+        .reg_bits = 16,
+        .val_bits = 8,
+};
+
+static struct gpio_chip template_chip = {
+        .label                  = "ts4900-gpio",
+        .owner                  = THIS_MODULE,
+        .get_direction          = ts4900_gpio_get_direction,
+        .direction_input        = ts4900_gpio_direction_input,
+        .direction_output       = ts4900_gpio_direction_output,
+        .get                    = ts4900_gpio_get,
+        .set                    = ts4900_gpio_set,
+        .base                   = -1,
+        .can_sleep              = true,
+};
+
+static const struct of_device_id ts4900_gpio_of_match_table[] = {
+        {
+                .compatible = "technologic,ts4900-gpio",
+                .data = (void *)TS4900_GPIO_IN,
+        }, {
+                .compatible = "technologic,ts7970-gpio",
+                .data = (void *)TS7970_GPIO_IN,
+        },
+        { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ts4900_gpio_of_match_table);
+
+static int ts4900_gpio_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        const struct of_device_id *match;
+        struct ts4900_gpio_priv *priv;
+        u32 ngpio;
+        int ret;
+
+        match = of_match_device(ts4900_gpio_of_match_table, &client->dev);
+        if (!match)
+                return -EINVAL;
+
+        if (of_property_read_u32(client->dev.of_node, "ngpios", &ngpio))
+                ngpio = DEFAULT_PIN_NUMBER;
+
+        priv = devm_kzalloc(&client->dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        priv->gpio_chip = template_chip;
+        priv->gpio_chip.label = "ts4900-gpio";
+        priv->gpio_chip.ngpio = ngpio;
+        priv->gpio_chip.parent = &client->dev;
+        priv->input_bit = (uintptr_t)match->data;
+
+        priv->regmap = devm_regmap_init_i2c(client, &ts4900_regmap_config);
+        if (IS_ERR(priv->regmap)) {
+                ret = PTR_ERR(priv->regmap);
+                dev_err(&client->dev, "Failed to allocate register map: %d\n",
+                        ret);
+                return ret;
+        }
+
+        ret = devm_gpiochip_add_data(&client->dev, &priv->gpio_chip, priv);
+        if (ret < 0) {
+                dev_err(&client->dev, "Unable to register gpiochip\n");
+                return ret;
+        }
+
+        i2c_set_clientdata(client, priv);
+
+        return 0;
+}
+
+static const struct i2c_device_id ts4900_gpio_id_table[] = {
+        { "ts4900-gpio", },
+        { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(i2c, ts4900_gpio_id_table);
+
+static struct i2c_driver ts4900_gpio_driver = {
+        .driver = {
+                .name = "ts4900-gpio",
+                .of_match_table = ts4900_gpio_of_match_table,
+        },
+        .probe = ts4900_gpio_probe,
+        .id_table = ts4900_gpio_id_table,
+};
+module_i2c_driver(ts4900_gpio_driver);
+
+MODULE_AUTHOR("Technologic Systems");
+MODULE_DESCRIPTION("GPIO interface for Technologic Systems I2C-FPGA core");
+MODULE_LICENSE("GPL");