Initial import

1 files changed, 197 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
new file mode 100644
index 000000000..e3d968f75
--- /dev/null
+++ b/drivers/gpio/gpio-74x164.c
@@ -0,0 +1,197 @@
+/*
+ *  74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver
+ *
+ *  Copyright (C) 2010 Gabor Juhos <juhosg@openwrt.org>
+ *  Copyright (C) 2010 Miguel Gaio <miguel.gaio@efixo.com>
+ *
+ *  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.
+ */
+
+#include <linux/init.h>
+#include <linux/mutex.h>
+#include <linux/spi/spi.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/slab.h>
+#include <linux/module.h>
+
+#define GEN_74X164_NUMBER_GPIOS	8
+
+struct gen_74x164_chip {
+	u8			*buffer;
+	struct gpio_chip	gpio_chip;
+	struct mutex		lock;
+	u32			registers;
+};
+
+static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
+{
+	return container_of(gc, struct gen_74x164_chip, gpio_chip);
+}
+
+static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
+{
+	struct spi_device *spi = to_spi_device(chip->gpio_chip.dev);
+	struct spi_message message;
+	struct spi_transfer *msg_buf;
+	int i, ret = 0;
+
+	msg_buf = kzalloc(chip->registers * sizeof(struct spi_transfer),
+			GFP_KERNEL);
+	if (!msg_buf)
+		return -ENOMEM;
+
+	spi_message_init(&message);
+
+	/*
+	 * Since the registers are chained, every byte sent will make
+	 * the previous byte shift to the next register in the
+	 * chain. Thus, the first byte send will end up in the last
+	 * register at the end of the transfer. So, to have a logical
+	 * numbering, send the bytes in reverse order so that the last
+	 * byte of the buffer will end up in the last register.
+	 */
+	for (i = chip->registers - 1; i >= 0; i--) {
+		msg_buf[i].tx_buf = chip->buffer + i;
+		msg_buf[i].len = sizeof(u8);
+		spi_message_add_tail(msg_buf + i, &message);
+	}
+
+	ret = spi_sync(spi, &message);
+
+	kfree(msg_buf);
+
+	return ret;
+}
+
+static int gen_74x164_get_value(struct gpio_chip *gc, unsigned offset)
+{
+	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
+	u8 bank = offset / 8;
+	u8 pin = offset % 8;
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ret = (chip->buffer[bank] >> pin) & 0x1;
+	mutex_unlock(&chip->lock);
+
+	return ret;
+}
+
+static void gen_74x164_set_value(struct gpio_chip *gc,
+		unsigned offset, int val)
+{
+	struct gen_74x164_chip *chip = gpio_to_74x164_chip(gc);
+	u8 bank = offset / 8;
+	u8 pin = offset % 8;
+
+	mutex_lock(&chip->lock);
+	if (val)
+		chip->buffer[bank] |= (1 << pin);
+	else
+		chip->buffer[bank] &= ~(1 << pin);
+
+	__gen_74x164_write_config(chip);
+	mutex_unlock(&chip->lock);
+}
+
+static int gen_74x164_direction_output(struct gpio_chip *gc,
+		unsigned offset, int val)
+{
+	gen_74x164_set_value(gc, offset, val);
+	return 0;
+}
+
+static int gen_74x164_probe(struct spi_device *spi)
+{
+	struct gen_74x164_chip *chip;
+	int ret;
+
+	/*
+	 * bits_per_word cannot be configured in platform data
+	 */
+	spi->bits_per_word = 8;
+
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return ret;
+
+	chip = devm_kzalloc(&spi->dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	spi_set_drvdata(spi, chip);
+
+	chip->gpio_chip.label = spi->modalias;
+	chip->gpio_chip.direction_output = gen_74x164_direction_output;
+	chip->gpio_chip.get = gen_74x164_get_value;
+	chip->gpio_chip.set = gen_74x164_set_value;
+	chip->gpio_chip.base = -1;
+
+	if (of_property_read_u32(spi->dev.of_node, "registers-number",
+				 &chip->registers)) {
+		dev_err(&spi->dev,
+			"Missing registers-number property in the DT.\n");
+		return -EINVAL;
+	}
+
+	chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
+	chip->buffer = devm_kzalloc(&spi->dev, chip->registers, GFP_KERNEL);
+	if (!chip->buffer)
+		return -ENOMEM;
+
+	chip->gpio_chip.can_sleep = true;
+	chip->gpio_chip.dev = &spi->dev;
+	chip->gpio_chip.owner = THIS_MODULE;
+
+	mutex_init(&chip->lock);
+
+	ret = __gen_74x164_write_config(chip);
+	if (ret) {
+		dev_err(&spi->dev, "Failed writing: %d\n", ret);
+		goto exit_destroy;
+	}
+
+	ret = gpiochip_add(&chip->gpio_chip);
+	if (!ret)
+		return 0;
+
+exit_destroy:
+	mutex_destroy(&chip->lock);
+
+	return ret;
+}
+
+static int gen_74x164_remove(struct spi_device *spi)
+{
+	struct gen_74x164_chip *chip = spi_get_drvdata(spi);
+
+	gpiochip_remove(&chip->gpio_chip);
+	mutex_destroy(&chip->lock);
+
+	return 0;
+}
+
+static const struct of_device_id gen_74x164_dt_ids[] = {
+	{ .compatible = "fairchild,74hc595" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gen_74x164_dt_ids);
+
+static struct spi_driver gen_74x164_driver = {
+	.driver = {
+		.name		= "74x164",
+		.owner		= THIS_MODULE,
+		.of_match_table	= gen_74x164_dt_ids,
+	},
+	.probe		= gen_74x164_probe,
+	.remove		= gen_74x164_remove,
+};
+module_spi_driver(gen_74x164_driver);
+
+MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
+MODULE_AUTHOR("Miguel Gaio <miguel.gaio@efixo.com>");
+MODULE_DESCRIPTION("GPIO expander driver for 74X164 8-bits shift register");
+MODULE_LICENSE("GPL v2");