i2c: Add bus recovery infrastructure

[karo-tx-linux.git] / drivers / i2c / i2c-core.c

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index f7dfe878a51b06e730fd635922b32785f7f20520..0d873ba2e82e61b87584b5d7ae5af09e4f38f27b 100644 (file)
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -27,7 +27,9 @@
 
 #include <linux/module.h>
 #include <linux/kernel.h>
+#include <linux/delay.h>
 #include <linux/errno.h>
+#include <linux/gpio.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
@@ -109,6 +111,130 @@ static int i2c_device_uevent(struct device *dev, struct kobj_uevent_env *env)
 #define i2c_device_uevent      NULL
 #endif /* CONFIG_HOTPLUG */
 
+/* i2c bus recovery routines */
+static int get_scl_gpio_value(struct i2c_adapter *adap)
+{
+       return gpio_get_value(adap->bus_recovery_info->scl_gpio);
+}
+
+static void set_scl_gpio_value(struct i2c_adapter *adap, int val)
+{
+       gpio_set_value(adap->bus_recovery_info->scl_gpio, val);
+}
+
+static int get_sda_gpio_value(struct i2c_adapter *adap)
+{
+       return gpio_get_value(adap->bus_recovery_info->sda_gpio);
+}
+
+static int i2c_get_gpios_for_recovery(struct i2c_adapter *adap)
+{
+       struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+       struct device *dev = &adap->dev;
+       int ret = 0;
+
+       ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
+                       GPIOF_OUT_INIT_HIGH, "i2c-scl");
+       if (ret) {
+               dev_warn(dev, "Can't get SCL gpio: %d\n", bri->scl_gpio);
+               return ret;
+       }
+
+       if (bri->get_sda) {
+               if (gpio_request_one(bri->sda_gpio, GPIOF_IN, "i2c-sda")) {
+                       /* work without SDA polling */
+                       dev_warn(dev, "Can't get SDA gpio: %d. Not using SDA polling\n",
+                                       bri->sda_gpio);
+                       bri->get_sda = NULL;
+               }
+       }
+
+       return ret;
+}
+
+static void i2c_put_gpios_for_recovery(struct i2c_adapter *adap)
+{
+       struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+
+       if (bri->get_sda)
+               gpio_free(bri->sda_gpio);
+
+       gpio_free(bri->scl_gpio);
+}
+
+/*
+ * We are generating clock pulses. ndelay() determines durating of clk pulses.
+ * We will generate clock with rate 100 KHz and so duration of both clock levels
+ * is: delay in ns = (10^6 / 100) / 2
+ */
+#define RECOVERY_NDELAY                5000
+#define RECOVERY_CLK_CNT       9
+
+static int i2c_generic_recovery(struct i2c_adapter *adap)
+{
+       struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+       int i = 0, val = 1, ret = 0;
+
+       if (bri->prepare_recovery)
+               bri->prepare_recovery(bri);
+
+       /*
+        * By this time SCL is high, as we need to give 9 falling-rising edges
+        */
+       while (i++ < RECOVERY_CLK_CNT * 2) {
+               if (val) {
+                       /* Break if SDA is high */
+                       if (bri->get_sda && bri->get_sda(adap))
+                                       break;
+                       /* SCL shouldn't be low here */
+                       if (!bri->get_scl(adap)) {
+                               dev_err(&adap->dev,
+                                       "SCL is stuck low, exit recovery\n");
+                               ret = -EBUSY;
+                               break;
+                       }
+               }
+
+               val = !val;
+               bri->set_scl(adap, val);
+               ndelay(RECOVERY_NDELAY);
+       }
+
+       if (bri->unprepare_recovery)
+               bri->unprepare_recovery(bri);
+
+       return ret;
+}
+
+int i2c_generic_scl_recovery(struct i2c_adapter *adap)
+{
+       adap->bus_recovery_info->set_scl(adap, 1);
+       return i2c_generic_recovery(adap);
+}
+
+int i2c_generic_gpio_recovery(struct i2c_adapter *adap)
+{
+       int ret;
+
+       ret = i2c_get_gpios_for_recovery(adap);
+       if (ret)
+               return ret;
+
+       ret = i2c_generic_recovery(adap);
+       i2c_put_gpios_for_recovery(adap);
+
+       return ret;
+}
+
+int i2c_recover_bus(struct i2c_adapter *adap)
+{
+       if (!adap->bus_recovery_info)
+               return -EOPNOTSUPP;
+
+       dev_dbg(&adap->dev, "Trying i2c bus recovery\n");
+       return adap->bus_recovery_info->recover_bus(adap);
+}
+
 static int i2c_device_probe(struct device *dev)
 {
        struct i2c_client       *client = i2c_verify_client(dev);
@@ -902,6 +1028,39 @@ static int i2c_register_adapter(struct i2c_adapter *adap)
                         "Failed to create compatibility class link\n");
 #endif
 
+       /* bus recovery specific initialization */
+       if (adap->bus_recovery_info) {
+               struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+
+               if (!bri->recover_bus) {
+                       dev_err(&adap->dev, "No recover_bus() found, not using recovery\n");
+                       adap->bus_recovery_info = NULL;
+                       goto exit_recovery;
+               }
+
+               /* Generic GPIO recovery */
+               if (bri->recover_bus == i2c_generic_gpio_recovery) {
+                       if (!gpio_is_valid(bri->scl_gpio)) {
+                               dev_err(&adap->dev, "Invalid SCL gpio, not using recovery\n");
+                               adap->bus_recovery_info = NULL;
+                               goto exit_recovery;
+                       }
+
+                       if (gpio_is_valid(bri->sda_gpio))
+                               bri->get_sda = get_sda_gpio_value;
+                       else
+                               bri->get_sda = NULL;
+
+                       bri->get_scl = get_scl_gpio_value;
+                       bri->set_scl = set_scl_gpio_value;
+               } else if (!bri->set_scl || !bri->get_scl) {
+                       /* Generic SCL recovery */
+                       dev_err(&adap->dev, "No {get|set}_gpio() found, not using recovery\n");
+                       adap->bus_recovery_info = NULL;
+               }
+       }
+
+exit_recovery:
        /* create pre-declared device nodes */
        if (adap->nr < __i2c_first_dynamic_bus_num)
                i2c_scan_static_board_info(adap);