[patch 2.6.24-rc6-mm 8/9] gpiolib: pca9539 i2c gpio expander support

David Brownell
2007-12-29T04:07:40Z

From: eric miao <eric.miao@marvell.com>

This adds a new-style I2C driver with basic support for the sixteen
bit PCA9539 GPIO expanders. These chips have multiple registers,
push-pull output drivers, and (not supported by this patch) pin
change interrupts.

Board-specific code must provide "pca9539_platform_data" with each
chip's "i2c_board_info". That provides the GPIO numbers to be used
by that chip, and callbacks for board-specific setup/teardown logic.

Derived from drivers/i2c/chips/pca9539.c (which has no current known
users). This is faster and simpler; it uses 16-bit register access,
and caches the OUTPUT and DIRECTION registers for fast access.

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
---
drivers/gpio/Kconfig | 10 +
drivers/gpio/Makefile | 1
drivers/gpio/pca9539.c | 264 ++++++++++++++++++++++++++++++++++++++++++++
include/linux/i2c/pca9539.h | 18 +++
4 files changed, 293 insertions(+)

--- at91.orig/drivers/gpio/Kconfig
+++ at91/drivers/gpio/Kconfig
@@ -27,6 +27,16 @@ config DEBUG_GPIO

comment "I2C GPIO expanders:"

+config GPIO_PCA9539
+ tristate "PCA9539 16-bit I/O port"
+ depends on I2C
+ help
+ Say yes here to support the PCA9539 16-bit I/O port. These
+ parts are made by NXP and TI.
+
+ This driver can also be built as a module. If so, the module
+ will be called pca9539.
+
config GPIO_PCF857X
tristate "PCF857x, PCA857x, and PCA967x I2C GPIO expanders"
depends on I2C
--- at91.orig/drivers/gpio/Makefile
+++ at91/drivers/gpio/Makefile
@@ -1,6 +1,7 @@
# gpio support: dedicated expander chips, etc

obj-$(CONFIG_GPIO_MCP23S08) += mcp23s08.o
+obj-$(CONFIG_GPIO_PCA9539) += pca9539.o
obj-$(CONFIG_GPIO_PCF857X) += pcf857x.o

ifeq ($(CONFIG_DEBUG_GPIO),y)
--- /dev/null
+++ at91/drivers/gpio/pca9539.c
@@ -0,0 +1,264 @@
+/*
+ * pca9539.c - 16-bit I/O port with interrupt and reset
+ *
+ * Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+ * Copyright (C) 2007 Marvell International Ltd.
+ *
+ * Derived from drivers/i2c/chips/pca9539.c
+ *
+ * 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/module.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+#include <linux/i2c/pca9539.h>
+
+#include <asm/gpio.h>
+
+
+#define NR_PCA9539_GPIOS 16
+
+#define PCA9539_INPUT 0
+#define PCA9539_OUTPUT 2
+#define PCA9539_INVERT 4
+#define PCA9539_DIRECTION 6
+
+struct pca9539_chip {
+ unsigned gpio_start;
+ uint16_t reg_output;
+ uint16_t reg_direction;
+
+ struct i2c_client *client;
+ struct gpio_chip gpio_chip;
+};
+
+/* NOTE: we can't currently rely on fault codes to come from SMBus
+ * calls, so we map all errors to EIO here and return zero otherwise.
+ */
+static int pca9539_write_reg(struct pca9539_chip *chip, int reg, uint16_t val)
+{
+ if (i2c_smbus_write_word_data(chip->client, reg, val) < 0)
+ return -EIO;
+ else
+ return 0;
+}
+
+static int pca9539_read_reg(struct pca9539_chip *chip, int reg, uint16_t *val)
+{
+ int ret;
+
+ ret = i2c_smbus_read_word_data(chip->client, reg);
+ if (ret < 0) {
+ dev_err(&chip->client->dev, "failed reading register\n");
+ return -EIO;
+ }
+
+ *val = (uint16_t)ret;
+ return 0;
+}
+
+static int pca9539_gpio_direction_input(struct gpio_chip *gc, unsigned off)
+{
+ struct pca9539_chip *chip;
+ uint16_t reg_val;
+ int ret;
+
+ chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+ reg_val = chip->reg_direction | (1u << off);
+ ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+ if (ret)
+ return ret;
+
+ chip->reg_direction = reg_val;
+ return 0;
+}
+
+static int pca9539_gpio_direction_output(struct gpio_chip *gc,
+ unsigned off, int val)
+{
+ struct pca9539_chip *chip;
+ uint16_t reg_val;
+ int ret;
+
+ chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+ /* set output level */
+ if (val)
+ reg_val = chip->reg_output | (1u << off);
+ else
+ reg_val = chip->reg_output & ~(1u << off);
+
+ ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+ if (ret)
+ return ret;
+
+ chip->reg_output = reg_val;
+
+ /* then direction */
+ reg_val = chip->reg_direction & ~(1u << off);
+ ret = pca9539_write_reg(chip, PCA9539_DIRECTION, reg_val);
+ if (ret)
+ return ret;
+
+ chip->reg_direction = reg_val;
+ return 0;
+}
+
+static int pca9539_gpio_get_value(struct gpio_chip *gc, unsigned off)
+{
+ struct pca9539_chip *chip;
+ uint16_t reg_val;
+ int ret;
+
+ chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+ ret = pca9539_read_reg(chip, PCA9539_INPUT, &reg_val);
+ if (ret < 0) {
+ /* NOTE: diagnostic already omitted; that's the
+ * best we can do here.
+ */
+ return 0;
+ }
+
+ return (reg_val & (1u << off)) ? 1 : 0;
+}
+
+static void pca9539_gpio_set_value(struct gpio_chip *gc, unsigned off, int val)
+{
+ struct pca9539_chip *chip;
+ uint16_t reg_val;
+ int ret;
+
+ chip = container_of(gc, struct pca9539_chip, gpio_chip);
+
+ if (val)
+ reg_val = chip->reg_output | (1u << off);
+ else
+ reg_val = chip->reg_output & ~(1u << off);
+
+ ret = pca9539_write_reg(chip, PCA9539_OUTPUT, reg_val);
+ if (ret)
+ return;
+
+ chip->reg_output = reg_val;
+}
+
+static int pca9539_init_gpio(struct pca9539_chip *chip)
+{
+ struct gpio_chip *gc;
+
+ gc = &chip->gpio_chip;
+
+ gc->direction_input = pca9539_gpio_direction_input;
+ gc->direction_output = pca9539_gpio_direction_output;
+ gc->get = pca9539_gpio_get_value;
+ gc->set = pca9539_gpio_set_value;
+
+ gc->base = chip->gpio_start;
+ gc->ngpio = NR_PCA9539_GPIOS;
+ gc->label = "pca9539";
+
+ return gpiochip_add(gc);
+}
+
+static int __devinit pca9539_probe(struct i2c_client *client)
+{
+ struct pca9539_platform_data *pdata;
+ struct pca9539_chip *chip;
+ int ret;
+
+ pdata = client->dev.platform_data;
+ if (pdata == NULL)
+ return -ENODEV;
+
+ chip = kzalloc(sizeof(struct pca9539_chip), GFP_KERNEL);
+ if (chip == NULL)
+ return -ENOMEM;
+
+ chip->client = client;
+
+ chip->gpio_start = pdata->gpio_base;
+
+ /* initialize cached registers from their original values */
+ ret = pca9539_read_reg(chip, PCA9539_OUTPUT, &chip->reg_output);
+ if (ret)
+ goto out_failed;
+
+ ret = pca9539_read_reg(chip, PCA9539_DIRECTION, &chip->reg_direction);
+ if (ret)
+ goto out_failed;
+
+ /* set platform specific polarity inversion */
+ ret = pca9539_write_reg(chip, PCA9539_INVERT, pdata->invert);
+ if (ret)
+ goto out_failed;
+
+ ret = pca9539_init_gpio(chip);
+ if (ret)
+ goto out_failed;
+
+ if (pdata->setup) {
+ ret = pdata->setup(client, chip->gpio_chip.base,
+ chip->gpio_chip.ngpio, pdata->context);
+ if (ret < 0)
+ dev_dbg(&client->dev, "setup failed, %d\n", ret);
+ }
+
+ i2c_set_clientdata(client, chip);
+ return 0;
+
+out_failed:
+ kfree(chip);
+ return ret;
+}
+
+static int pca9539_remove(struct i2c_client *client)
+{
+ struct pca9539_platform_data *pdata = client->dev.platform_data;
+ struct pca9539_chip *chip = i2c_get_clientdata(client);
+ int ret = 0;
+
+ if (pdata->teardown) {
+ ret = pdata->teardown(client, chip->gpio_chip.base,
+ chip->gpio_chip.ngpio, pdata->context);
+ if (ret < 0)
+ dev_dbg(&client->dev, "teardown failed, %d\n", ret);
+ }
+
+ ret = gpiochip_remove(&chip->gpio_chip);
+ if (ret) {
+ dev_err(&client->dev, "failed remove gpio_chip\n");
+ return ret;
+ }
+
+ kfree(chip);
+ return 0;
+}
+
+static struct i2c_driver pca9539_driver = {
+ .driver = {
+ .name = "pca9539",
+ },
+ .probe = pca9539_probe,
+ .remove = pca9539_remove,
+};
+
+static int __init pca9539_init(void)
+{
+ return i2c_add_driver(&pca9539_driver);
+}
+module_init(pca9539_init);
+
+static void __exit pca9539_exit(void)
+{
+ i2c_del_driver(&pca9539_driver);
+}
+module_exit(pca9539_exit);
+
+MODULE_AUTHOR("eric miao <eric.miao@marvell.com>");
+MODULE_DESCRIPTION("GPIO expander driver for PCA9539");
+MODULE_LICENSE("GPL");
--- /dev/null
+++ at91/include/linux/i2c/pca9539.h
@@ -0,0 +1,18 @@
+/* platform data for the PCA9539 16-bit I/O expander driver */
+
+struct pca9539_platform_data {
+ /* number of the first GPIO */
+ unsigned gpio_base;
+
+ /* initial polarity inversion setting */
+ uint16_t invert;
+
+ void *context; /* param to setup/teardown */
+
+ int (*setup)(struct i2c_client *client,
+ unsigned gpio, unsigned ngpio,
+ void *context);
+ int (*teardown)(struct i2c_client *client,
+ unsigned gpio, unsigned ngpio,
+ void *context);
+};