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>
diff --git a/drivers/gpio/gpio-it87.c b/drivers/gpio/gpio-it87.c
new file mode 100644
index 0000000..21f6f7c
--- /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");