gpio: add GPIO support for IT87xx, replacing gpio-it8761e

This patch adds support for the GPIOs found on the ITE super-I/O chips
IT87xx.

Signed-off-by: Diego Elio Pettenò <flameeyes@flameeyes.eu>
Signed-off-by: Christophe Vu-Brugier <cvubrugier@fastmail.fm>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 411 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-it87.c b/drivers/gpio/gpio-it87.c
new file mode 100644
index 000000000000..21f6f7c0eb34
--- /dev/null
+++ b/drivers/gpio/gpio-it87.c
@@ -0,0 +1,411 @@
+/*
+ *  GPIO interface for IT87xx Super I/O chips
+ *
+ *  Author: Diego Elio Pettenò <flameeyes@flameeyes.eu>
+ *
+ *  Based on it87_wdt.c     by Oliver Schuster
+ *           gpio-it8761e.c by Denis Turischev
+ *           gpio-stmpe.c   by Rabin Vincent
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License 2 as published
+ *  by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; see the file COPYING.  If not, write to
+ *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/errno.h>
+#include <linux/ioport.h>
+#include <linux/slab.h>
+#include <linux/gpio.h>
+
+/* Chip Id numbers */
+#define NO_DEV_ID	0xffff
+#define IT8728_ID	0x8728
+#define IT8732_ID	0x8732
+#define IT8761_ID	0x8761
+
+/* IO Ports */
+#define REG		0x2e
+#define VAL		0x2f
+
+/* Logical device Numbers LDN */
+#define GPIO		0x07
+
+/* Configuration Registers and Functions */
+#define LDNREG		0x07
+#define CHIPID		0x20
+#define CHIPREV		0x22
+
+/**
+ * struct it87_gpio - it87-specific GPIO chip
+ * @chip the underlying gpio_chip structure
+ * @lock a lock to avoid races between operations
+ * @io_base base address for gpio ports
+ * @io_size size of the port rage starting from io_base.
+ * @output_base Super I/O register address for Output Enable register
+ * @simple_base Super I/O 'Simple I/O' Enable register
+ * @simple_size Super IO 'Simple I/O' Enable register size; this is
+ *	required because IT87xx chips might only provide Simple I/O
+ *	switches on a subset of lines, whereas the others keep the
+ *	same status all time.
+ */
+struct it87_gpio {
+	struct gpio_chip chip;
+	spinlock_t lock;
+	u16 io_base;
+	u16 io_size;
+	u8 output_base;
+	u8 simple_base;
+	u8 simple_size;
+};
+
+static struct it87_gpio it87_gpio_chip = {
+	.lock = __SPIN_LOCK_UNLOCKED(it87_gpio_chip.lock),
+};
+
+static inline struct it87_gpio *to_it87_gpio(struct gpio_chip *chip)
+{
+	return container_of(chip, struct it87_gpio, chip);
+}
+
+/* Superio chip access functions; copied from wdt_it87 */
+
+static inline int superio_enter(void)
+{
+	/*
+	 * Try to reserve REG and REG + 1 for exclusive access.
+	 */
+	if (!request_muxed_region(REG, 2, KBUILD_MODNAME))
+		return -EBUSY;
+
+	outb(0x87, REG);
+	outb(0x01, REG);
+	outb(0x55, REG);
+	outb(0x55, REG);
+	return 0;
+}
+
+static inline void superio_exit(void)
+{
+	outb(0x02, REG);
+	outb(0x02, VAL);
+	release_region(REG, 2);
+}
+
+static inline void superio_select(int ldn)
+{
+	outb(LDNREG, REG);
+	outb(ldn, VAL);
+}
+
+static inline int superio_inb(int reg)
+{
+	outb(reg, REG);
+	return inb(VAL);
+}
+
+static inline void superio_outb(int val, int reg)
+{
+	outb(reg, REG);
+	outb(val, VAL);
+}
+
+static inline int superio_inw(int reg)
+{
+	int val;
+
+	outb(reg++, REG);
+	val = inb(VAL) << 8;
+	outb(reg, REG);
+	val |= inb(VAL);
+	return val;
+}
+
+static inline void superio_outw(int val, int reg)
+{
+	outb(reg++, REG);
+	outb(val >> 8, VAL);
+	outb(reg, REG);
+	outb(val, VAL);
+}
+
+static inline void superio_set_mask(int mask, int reg)
+{
+	u8 curr_val = superio_inb(reg);
+	u8 new_val = curr_val | mask;
+
+	if (curr_val != new_val)
+		superio_outb(new_val, reg);
+}
+
+static inline void superio_clear_mask(int mask, int reg)
+{
+	u8 curr_val = superio_inb(reg);
+	u8 new_val = curr_val & ~mask;
+
+	if (curr_val != new_val)
+		superio_outb(new_val, reg);
+}
+
+static int it87_gpio_request(struct gpio_chip *chip, unsigned gpio_num)
+{
+	u8 mask, group;
+	int rc = 0;
+	struct it87_gpio *it87_gpio = to_it87_gpio(chip);
+
+	mask = 1 << (gpio_num % 8);
+	group = (gpio_num / 8);
+
+	spin_lock(&it87_gpio->lock);
+
+	rc = superio_enter();
+	if (rc)
+		goto exit;
+
+	/* not all the IT87xx chips support Simple I/O and not all of
+	 * them allow all the lines to be set/unset to Simple I/O.
+	 */
+	if (group < it87_gpio->simple_size)
+		superio_set_mask(mask, group + it87_gpio->simple_base);
+
+	/* clear output enable, setting the pin to input, as all the
+	 * newly-exported GPIO interfaces are set to input.
+	 */
+	superio_clear_mask(mask, group + it87_gpio->output_base);
+
+	superio_exit();
+
+exit:
+	spin_unlock(&it87_gpio->lock);
+	return rc;
+}
+
+static int it87_gpio_get(struct gpio_chip *chip, unsigned gpio_num)
+{
+	u16 reg;
+	u8 mask;
+	struct it87_gpio *it87_gpio = to_it87_gpio(chip);
+
+	mask = 1 << (gpio_num % 8);
+	reg = (gpio_num / 8) + it87_gpio->io_base;
+
+	return !!(inb(reg) & mask);
+}
+
+static int it87_gpio_direction_in(struct gpio_chip *chip, unsigned gpio_num)
+{
+	u8 mask, group;
+	int rc = 0;
+	struct it87_gpio *it87_gpio = to_it87_gpio(chip);
+
+	mask = 1 << (gpio_num % 8);
+	group = (gpio_num / 8);
+
+	spin_lock(&it87_gpio->lock);
+
+	rc = superio_enter();
+	if (rc)
+		goto exit;
+
+	/* clear the output enable bit */
+	superio_clear_mask(mask, group + it87_gpio->output_base);
+
+	superio_exit();
+
+exit:
+	spin_unlock(&it87_gpio->lock);
+	return rc;
+}
+
+static void it87_gpio_set(struct gpio_chip *chip,
+			  unsigned gpio_num, int val)
+{
+	u8 mask, curr_vals;
+	u16 reg;
+	struct it87_gpio *it87_gpio = to_it87_gpio(chip);
+
+	mask = 1 << (gpio_num % 8);
+	reg = (gpio_num / 8) + it87_gpio->io_base;
+
+	curr_vals = inb(reg);
+	if (val)
+		outb(curr_vals | mask, reg);
+	else
+		outb(curr_vals & ~mask, reg);
+}
+
+static int it87_gpio_direction_out(struct gpio_chip *chip,
+				   unsigned gpio_num, int val)
+{
+	u8 mask, group;
+	int rc = 0;
+	struct it87_gpio *it87_gpio = to_it87_gpio(chip);
+
+	mask = 1 << (gpio_num % 8);
+	group = (gpio_num / 8);
+
+	spin_lock(&it87_gpio->lock);
+
+	rc = superio_enter();
+	if (rc)
+		goto exit;
+
+	/* set the output enable bit */
+	superio_set_mask(mask, group + it87_gpio->output_base);
+
+	it87_gpio_set(chip, gpio_num, val);
+
+	superio_exit();
+
+exit:
+	spin_unlock(&it87_gpio->lock);
+	return rc;
+}
+
+static struct gpio_chip it87_template_chip = {
+	.label			= KBUILD_MODNAME,
+	.owner			= THIS_MODULE,
+	.request		= it87_gpio_request,
+	.get			= it87_gpio_get,
+	.direction_input	= it87_gpio_direction_in,
+	.set			= it87_gpio_set,
+	.direction_output	= it87_gpio_direction_out,
+	.base			= -1
+};
+
+static int __init it87_gpio_init(void)
+{
+	int rc = 0, i;
+	u16 chip_type;
+	u8 chip_rev, gpio_ba_reg;
+	char *labels, **labels_table;
+
+	struct it87_gpio *it87_gpio = &it87_gpio_chip;
+
+	rc = superio_enter();
+	if (rc)
+		return rc;
+
+	chip_type = superio_inw(CHIPID);
+	chip_rev  = superio_inb(CHIPREV) & 0x0f;
+	superio_exit();
+
+	it87_gpio->chip = it87_template_chip;
+
+	switch (chip_type) {
+	case IT8728_ID:
+	case IT8732_ID:
+		gpio_ba_reg = 0x62;
+		it87_gpio->io_size = 8;
+		it87_gpio->output_base = 0xc8;
+		it87_gpio->simple_base = 0xc0;
+		it87_gpio->simple_size = 5;
+		it87_gpio->chip.ngpio = 64;
+		break;
+	case IT8761_ID:
+		gpio_ba_reg = 0x60;
+		it87_gpio->io_size = 4;
+		it87_gpio->output_base = 0xf0;
+		it87_gpio->simple_size = 0;
+		it87_gpio->chip.ngpio = 16;
+		break;
+	case NO_DEV_ID:
+		pr_err("no device\n");
+		return -ENODEV;
+	default:
+		pr_err("Unknown Chip found, Chip %04x Revision %x\n",
+		       chip_type, chip_rev);
+		return -ENODEV;
+	}
+
+	rc = superio_enter();
+	if (rc)
+		return rc;
+
+	superio_select(GPIO);
+
+	/* fetch GPIO base address */
+	it87_gpio->io_base = superio_inw(gpio_ba_reg);
+
+	superio_exit();
+
+	pr_info("Found Chip IT%04x rev %x. %u GPIO lines starting at %04xh\n",
+		chip_type, chip_rev, it87_gpio->chip.ngpio,
+		it87_gpio->io_base);
+
+	if (!request_region(it87_gpio->io_base, it87_gpio->io_size,
+							KBUILD_MODNAME))
+		return -EBUSY;
+
+	/* Set up aliases for the GPIO connection.
+	 *
+	 * ITE documentation for recent chips such as the IT8728F
+	 * refers to the GPIO lines as GPxy, with a coordinates system
+	 * where x is the GPIO group (starting from 1) and y is the
+	 * bit within the group.
+	 *
+	 * By creating these aliases, we make it easier to understand
+	 * to which GPIO pin we're referring to.
+	 */
+	labels = kcalloc(it87_gpio->chip.ngpio, sizeof("it87_gpXY"),
+								GFP_KERNEL);
+	labels_table = kcalloc(it87_gpio->chip.ngpio, sizeof(const char *),
+								GFP_KERNEL);
+
+	if (!labels || !labels_table) {
+		rc = -ENOMEM;
+		goto labels_free;
+	}
+
+	for (i = 0; i < it87_gpio->chip.ngpio; i++) {
+		char *label = &labels[i * sizeof("it87_gpXY")];
+
+		sprintf(label, "it87_gp%u%u", 1+(i/8), i%8);
+		labels_table[i] = label;
+	}
+
+	it87_gpio->chip.names = (const char *const*)labels_table;
+
+	rc = gpiochip_add(&it87_gpio->chip);
+	if (rc)
+		goto labels_free;
+
+	return 0;
+
+labels_free:
+	kfree(labels_table);
+	kfree(labels);
+	release_region(it87_gpio->io_base, it87_gpio->io_size);
+	return rc;
+}
+
+static void __exit it87_gpio_exit(void)
+{
+	struct it87_gpio *it87_gpio = &it87_gpio_chip;
+
+	gpiochip_remove(&it87_gpio->chip);
+	release_region(it87_gpio->io_base, it87_gpio->io_size);
+	kfree(it87_gpio->chip.names[0]);
+	kfree(it87_gpio->chip.names);
+}
+
+module_init(it87_gpio_init);
+module_exit(it87_gpio_exit);
+
+MODULE_AUTHOR("Diego Elio Pettenò <flameeyes@flameeyes.eu>");
+MODULE_DESCRIPTION("GPIO interface for IT87xx Super I/O chips");
+MODULE_LICENSE("GPL");