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path: root/drivers/gpio/gpio-ts4900.c
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Diffstat (limited to 'drivers/gpio/gpio-ts4900.c')
-rw-r--r--drivers/gpio/gpio-ts4900.c196
1 files changed, 196 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-ts4900.c b/drivers/gpio/gpio-ts4900.c
new file mode 100644
index 000000000..416725c26
--- /dev/null
+++ b/drivers/gpio/gpio-ts4900.c
@@ -0,0 +1,196 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Digital I/O driver for Technologic Systems I2C FPGA Core
+ *
+ * Copyright (C) 2015, 2018 Technologic Systems
+ * Copyright (C) 2016 Savoir-Faire Linux
+ */
+
+#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);
+
+ if (reg & TS4900_GPIO_OE)
+ return GPIO_LINE_DIRECTION_OUT;
+
+ return GPIO_LINE_DIRECTION_IN;
+}
+
+static int ts4900_gpio_direction_input(struct gpio_chip *chip,
+ unsigned int offset)
+{
+ struct ts4900_gpio_priv *priv = gpiochip_get_data(chip);
+
+ /*
+ * Only clear the OE bit here, requires a RMW. Prevents a potential issue
+ * with OE and DAT getting to the physical pin at different times.
+ */
+ return regmap_update_bits(priv->regmap, offset, TS4900_GPIO_OE, 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);
+ unsigned int reg;
+ int ret;
+
+ /*
+ * If changing from an input to an output, we need to first set the
+ * GPIO's DAT bit to what is requested and then set the OE bit. This
+ * prevents a glitch that can occur on the IO line.
+ */
+ regmap_read(priv->regmap, offset, &reg);
+ if (!(reg & TS4900_GPIO_OE)) {
+ if (value)
+ reg = TS4900_GPIO_OUT;
+ else
+ reg &= ~TS4900_GPIO_OUT;
+
+ regmap_write(priv->regmap, offset, reg);
+ }
+
+ 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 const 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)
+{
+ struct ts4900_gpio_priv *priv;
+ u32 ngpio;
+ int ret;
+
+ 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)of_device_get_match_data(&client->dev);
+
+ 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");