gpio: pcf857x: enable gpio_to_irq() support

pcf857x chip has some pins, but interrupt pin is only 1 pin.
And gpiolib requests 1 interrupt per 1 gpio pin.

Thus, this patch added demuxed irq to pcf857x driver,
and enabled gpio_to_irq().

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

2 files changed, 125 insertions, 0 deletions

diff --git a/drivers/gpio/gpio-pcf857x.c b/drivers/gpio/gpio-pcf857x.c
index 076e236d0da7..12e3e484d70b 100644
--- a/drivers/gpio/gpio-pcf857x.c
+++ b/drivers/gpio/gpio-pcf857x.c
@@ -23,7 +23,12 @@
 #include <linux/gpio.h>
 #include <linux/i2c.h>
 #include <linux/i2c/pcf857x.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqdomain.h>
 #include <linux/module.h>
+#include <linux/spinlock.h>
+#include <linux/workqueue.h>
 
 
 static const struct i2c_device_id pcf857x_id[] = {
@@ -60,7 +65,12 @@ struct pcf857x {
         struct gpio_chip        chip;
         struct i2c_client       *client;
         struct mutex            lock;           /* protect 'out' */
+        struct work_struct      work;           /* irq demux work */
+        struct irq_domain       *irq_domain;    /* for irq demux  */
+        spinlock_t              slock;          /* protect irq demux */
         unsigned                out;            /* software latch */
+        unsigned                status;         /* current status */
+        int                     irq;            /* real irq number */
 
         int (*write)(struct i2c_client *client, unsigned data);
         int (*read)(struct i2c_client *client);
@@ -150,6 +160,100 @@ static void pcf857x_set(struct gpio_chip *chip, unsigned offset, int value)
 
 /*-------------------------------------------------------------------------*/
 
+static int pcf857x_to_irq(struct gpio_chip *chip, unsigned offset)
+{
+        struct pcf857x *gpio = container_of(chip, struct pcf857x, chip);
+
+        return irq_create_mapping(gpio->irq_domain, offset);
+}
+
+static void pcf857x_irq_demux_work(struct work_struct *work)
+{
+        struct pcf857x *gpio = container_of(work,
+                                               struct pcf857x,
+                                               work);
+        unsigned long change, i, status, flags;
+
+        status = gpio->read(gpio->client);
+
+        spin_lock_irqsave(&gpio->slock, flags);
+
+        change = gpio->status ^ status;
+        for_each_set_bit(i, &change, gpio->chip.ngpio)
+                generic_handle_irq(irq_find_mapping(gpio->irq_domain, i));
+        gpio->status = status;
+
+        spin_unlock_irqrestore(&gpio->slock, flags);
+}
+
+static irqreturn_t pcf857x_irq_demux(int irq, void *data)
+{
+        struct pcf857x  *gpio = data;
+
+        /*
+         * pcf857x can't read/write data here,
+         * since i2c data access might go to sleep.
+         */
+        schedule_work(&gpio->work);
+
+        return IRQ_HANDLED;
+}
+
+static int pcf857x_irq_domain_map(struct irq_domain *domain, unsigned int virq,
+                                 irq_hw_number_t hw)
+{
+        irq_set_chip_and_handler(virq,
+                                 &dummy_irq_chip,
+                                 handle_level_irq);
+        return 0;
+}
+
+static struct irq_domain_ops pcf857x_irq_domain_ops = {
+        .map    = pcf857x_irq_domain_map,
+};
+
+static void pcf857x_irq_domain_cleanup(struct pcf857x *gpio)
+{
+        if (gpio->irq_domain)
+                irq_domain_remove(gpio->irq_domain);
+
+        if (gpio->irq)
+                free_irq(gpio->irq, gpio);
+}
+
+static int pcf857x_irq_domain_init(struct pcf857x *gpio,
+                                   struct pcf857x_platform_data *pdata,
+                                   struct device *dev)
+{
+        int status;
+
+        gpio->irq_domain = irq_domain_add_linear(dev->of_node,
+                                                 gpio->chip.ngpio,
+                                                 &pcf857x_irq_domain_ops,
+                                                 NULL);
+        if (!gpio->irq_domain)
+                goto fail;
+
+        /* enable real irq */
+        status = request_irq(pdata->irq, pcf857x_irq_demux, 0,
+                             dev_name(dev), gpio);
+        if (status)
+                goto fail;
+
+        /* enable gpio_to_irq() */
+        INIT_WORK(&gpio->work, pcf857x_irq_demux_work);
+        gpio->chip.to_irq       = pcf857x_to_irq;
+        gpio->irq               = pdata->irq;
+
+        return 0;
+
+fail:
+        pcf857x_irq_domain_cleanup(gpio);
+        return -EINVAL;
+}
+
+/*-------------------------------------------------------------------------*/
+
 static int pcf857x_probe(struct i2c_client *client,
                          const struct i2c_device_id *id)
 {
@@ -168,6 +272,7 @@ static int pcf857x_probe(struct i2c_client *client,
                 return -ENOMEM;
 
         mutex_init(&gpio->lock);
+        spin_lock_init(&gpio->slock);
 
         gpio->chip.base                 = pdata ? pdata->gpio_base : -1;
         gpio->chip.can_sleep            = 1;
@@ -179,6 +284,15 @@ static int pcf857x_probe(struct i2c_client *client,
         gpio->chip.direction_output     = pcf857x_output;
         gpio->chip.ngpio                = id->driver_data;
 
+        /* enable gpio_to_irq() if platform has settings */
+        if (pdata->irq) {
+                status = pcf857x_irq_domain_init(gpio, pdata, &client->dev);
+                if (status < 0) {
+                        dev_err(&client->dev, "irq_domain init failed\n");
+                        goto fail;
+                }
+        }
+
         /* NOTE:  the OnSemi jlc1562b is also largely compatible with
          * these parts, notably for output.  It has a low-resolution
          * DAC instead of pin change IRQs; and its inputs can be the
@@ -248,6 +362,7 @@ static int pcf857x_probe(struct i2c_client *client,
          * all-ones reset state.  Otherwise it flags pins to be driven low.
          */
         gpio->out = pdata ? ~pdata->n_latch : ~0;
+        gpio->status = gpio->out;
 
         status = gpiochip_add(&gpio->chip);
         if (status < 0)
@@ -278,6 +393,10 @@ static int pcf857x_probe(struct i2c_client *client,
 fail:
         dev_dbg(&client->dev, "probe error %d for '%s'\n",
                         status, client->name);
+
+        if (pdata->irq)
+                pcf857x_irq_domain_cleanup(gpio);
+
         kfree(gpio);
         return status;
 }
@@ -299,6 +418,9 @@ static int pcf857x_remove(struct i2c_client *client)
                 }
         }
 
+        if (pdata->irq)
+                pcf857x_irq_domain_cleanup(gpio);
+
         status = gpiochip_remove(&gpio->chip);
         if (status == 0)
                 kfree(gpio);
diff --git a/include/linux/i2c/pcf857x.h b/include/linux/i2c/pcf857x.h
index 0767a2a6b2f1..781e6bd06c34 100644
--- a/include/linux/i2c/pcf857x.h
+++ b/include/linux/i2c/pcf857x.h
@@ -10,6 +10,7 @@
  * @setup: optional callback issued once the GPIOs are valid
  * @teardown: optional callback issued before the GPIOs are invalidated
  * @context: optional parameter passed to setup() and teardown()
+ * @irq: optional interrupt number
  *
  * In addition to the I2C_BOARD_INFO() state appropriate to each chip,
  * the i2c_board_info used with the pcf875x driver must provide its
@@ -39,6 +40,8 @@ struct pcf857x_platform_data {
                                         int gpio, unsigned ngpio,
                                         void *context);
         void            *context;
+
+        int             irq;
 };
 
 #endif /* __LINUX_PCF857X_H */