1 files changed, 61 insertions, 7 deletions

diff --git a/drivers/gpio/gpio-74x164.c b/drivers/gpio/gpio-74x164.c
index 2e31bd35769a..ed3e55161bdc 100644
--- a/drivers/gpio/gpio-74x164.c
+++ b/drivers/gpio/gpio-74x164.c
@@ -14,14 +14,18 @@
 #include <linux/spi/spi.h>
 #include <linux/spi/74x164.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 {
         struct spi_device       *spi;
+        u8                      *buffer;
         struct gpio_chip        gpio_chip;
         struct mutex            lock;
-        u8                      port_config;
+        u32                     registers;
 };
 
 static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
@@ -31,17 +35,47 @@ static struct gen_74x164_chip *gpio_to_74x164_chip(struct gpio_chip *gc)
 
 static int __gen_74x164_write_config(struct gen_74x164_chip *chip)
 {
-        return spi_write(chip->spi,
-                         &chip->port_config, sizeof(chip->port_config));
+        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(chip->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->port_config >> offset) & 0x1;
+        ret = (chip->buffer[bank] >> pin) & 0x1;
         mutex_unlock(&chip->lock);
 
         return ret;
@@ -51,12 +85,14 @@ 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->port_config |= (1 << offset);
+                chip->buffer[bank] |= (1 << pin);
         else
-                chip->port_config &= ~(1 << offset);
+                chip->buffer[bank] &= ~(1 << pin);
 
         __gen_74x164_write_config(chip);
         mutex_unlock(&chip->lock);
@@ -75,6 +111,11 @@ static int __devinit gen_74x164_probe(struct spi_device *spi)
         struct gen_74x164_chip_platform_data *pdata;
         int ret;
 
+        if (!spi->dev.of_node) {
+                dev_err(&spi->dev, "No device tree data available.\n");
+                return -EINVAL;
+        }
+
         /*
          * bits_per_word cannot be configured in platform data
          */
@@ -104,7 +145,20 @@ static int __devinit gen_74x164_probe(struct spi_device *spi)
         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.ngpio = 8;
+
+        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");
+                ret = -EINVAL;
+                goto exit_destroy;
+        }
+
+        chip->gpio_chip.ngpio = GEN_74X164_NUMBER_GPIOS * chip->registers;
+        chip->buffer = devm_kzalloc(&spi->dev, chip->gpio_chip.ngpio, GFP_KERNEL);
+        if (!chip->buffer) {
+                ret = -ENOMEM;
+                goto exit_destroy;
+        }
+
         chip->gpio_chip.can_sleep = 1;
         chip->gpio_chip.dev = &spi->dev;
         chip->gpio_chip.owner = THIS_MODULE;