i2c: davinci: use ICPFUNC to toggle I2C as gpio for bus recovery

Having a board where the I2C bus locks up occasionally made it clear
that the bus recovery in the i2c-davinci driver will only work on
some boards, because on regular boards, this will only toggle GPIO
lines that aren't muxed to the actual pins.

The I2C controller on SoCs like da850 (and da830), Keystone 2 has the
built-in capability to bit-bang its lines by using the ICPFUNC registers
of the i2c controller.
Implement the suggested procedure by toggling SCL and checking SDA using
the ICPFUNC registers of the I2C controller when present. Allow platforms
to indicate the presence of the ICPFUNC registers with a has_pfunc platform
data flag and add optional DT property "ti,has-pfunc" to indicate
the same in DT.

Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Alexander Sverdlin <alexander.sverdlin@nokia.com>
Tested-by: Michael Lawnick <michael.lawnick@nokia.com>
Signed-off-by: Ben Gardiner <bengardiner@nanometrics.ca>
Signed-off-by: Mike Looijmans <milo-software@users.sourceforge.net>
[grygorii.strashko@ti.com: combined patches from Ben Gardiner and
Mike Looijmans and reimplemented ICPFUNC bus recovery using I2C
bus recovery infrastructure]
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 101 insertions, 1 deletions

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 54819fb4f82e..4788a32afb86 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -60,6 +60,12 @@
 #define DAVINCI_I2C_IVR_REG     0x28
 #define DAVINCI_I2C_EMDR_REG    0x2c
 #define DAVINCI_I2C_PSC_REG     0x30
+#define DAVINCI_I2C_FUNC_REG    0x48
+#define DAVINCI_I2C_DIR_REG     0x4c
+#define DAVINCI_I2C_DIN_REG     0x50
+#define DAVINCI_I2C_DOUT_REG    0x54
+#define DAVINCI_I2C_DSET_REG    0x58
+#define DAVINCI_I2C_DCLR_REG    0x5c
 
 #define DAVINCI_I2C_IVR_AAS     0x07
 #define DAVINCI_I2C_IVR_SCD     0x06
@@ -93,6 +99,29 @@
 #define DAVINCI_I2C_IMR_NACK    BIT(1)
 #define DAVINCI_I2C_IMR_AL      BIT(0)
 
+/* set SDA and SCL as GPIO */
+#define DAVINCI_I2C_FUNC_PFUNC0 BIT(0)
+
+/* set SCL as output when used as GPIO*/
+#define DAVINCI_I2C_DIR_PDIR0   BIT(0)
+/* set SDA as output when used as GPIO*/
+#define DAVINCI_I2C_DIR_PDIR1   BIT(1)
+
+/* read SCL GPIO level */
+#define DAVINCI_I2C_DIN_PDIN0 BIT(0)
+/* read SDA GPIO level */
+#define DAVINCI_I2C_DIN_PDIN1 BIT(1)
+
+/*set the SCL GPIO high */
+#define DAVINCI_I2C_DSET_PDSET0 BIT(0)
+/*set the SDA GPIO high */
+#define DAVINCI_I2C_DSET_PDSET1 BIT(1)
+
+/* set the SCL GPIO low */
+#define DAVINCI_I2C_DCLR_PDCLR0 BIT(0)
+/* set the SDA GPIO low */
+#define DAVINCI_I2C_DCLR_PDCLR1 BIT(1)
+
 struct davinci_i2c_dev {
         struct device           *dev;
         void __iomem            *base;
@@ -253,6 +282,71 @@ static struct i2c_bus_recovery_info davinci_i2c_gpio_recovery_info = {
         .unprepare_recovery = davinci_i2c_unprepare_recovery,
 };
 
+static void davinci_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+        struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+        if (val)
+                davinci_i2c_write_reg(dev, DAVINCI_I2C_DSET_REG,
+                                      DAVINCI_I2C_DSET_PDSET0);
+        else
+                davinci_i2c_write_reg(dev, DAVINCI_I2C_DCLR_REG,
+                                      DAVINCI_I2C_DCLR_PDCLR0);
+}
+
+static int davinci_i2c_get_scl(struct i2c_adapter *adap)
+{
+        struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+        int val;
+
+        /* read the state of SCL */
+        val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
+        return val & DAVINCI_I2C_DIN_PDIN0;
+}
+
+static int davinci_i2c_get_sda(struct i2c_adapter *adap)
+{
+        struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+        int val;
+
+        /* read the state of SDA */
+        val = davinci_i2c_read_reg(dev, DAVINCI_I2C_DIN_REG);
+        return val & DAVINCI_I2C_DIN_PDIN1;
+}
+
+static void davinci_i2c_scl_prepare_recovery(struct i2c_adapter *adap)
+{
+        struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+        davinci_i2c_prepare_recovery(adap);
+
+        /* SCL output, SDA input */
+        davinci_i2c_write_reg(dev, DAVINCI_I2C_DIR_REG, DAVINCI_I2C_DIR_PDIR0);
+
+        /* change to GPIO mode */
+        davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG,
+                              DAVINCI_I2C_FUNC_PFUNC0);
+}
+
+static void davinci_i2c_scl_unprepare_recovery(struct i2c_adapter *adap)
+{
+        struct davinci_i2c_dev *dev = i2c_get_adapdata(adap);
+
+        /* change back to I2C mode */
+        davinci_i2c_write_reg(dev, DAVINCI_I2C_FUNC_REG, 0);
+
+        davinci_i2c_unprepare_recovery(adap);
+}
+
+static struct i2c_bus_recovery_info davinci_i2c_scl_recovery_info = {
+        .recover_bus = i2c_generic_scl_recovery,
+        .set_scl = davinci_i2c_set_scl,
+        .get_scl = davinci_i2c_get_scl,
+        .get_sda = davinci_i2c_get_sda,
+        .prepare_recovery = davinci_i2c_scl_prepare_recovery,
+        .unprepare_recovery = davinci_i2c_scl_unprepare_recovery,
+};
+
 /*
  * Waiting for bus not busy
  */
@@ -660,6 +754,10 @@ static int davinci_i2c_probe(struct platform_device *pdev)
                 if (!of_property_read_u32(pdev->dev.of_node, "clock-frequency",
                         &prop))
                         dev->pdata->bus_freq = prop / 1000;
+
+                dev->pdata->has_pfunc =
+                        of_property_read_bool(pdev->dev.of_node,
+                                              "ti,has-pfunc");
         } else if (!dev->pdata) {
                 dev->pdata = &davinci_i2c_platform_data_default;
         }
@@ -701,7 +799,9 @@ static int davinci_i2c_probe(struct platform_device *pdev)
         adap->timeout = DAVINCI_I2C_TIMEOUT;
         adap->dev.of_node = pdev->dev.of_node;
 
-        if (dev->pdata->scl_pin) {
+        if (dev->pdata->has_pfunc)
+                adap->bus_recovery_info = &davinci_i2c_scl_recovery_info;
+        else if (dev->pdata->scl_pin) {
                 adap->bus_recovery_info = &davinci_i2c_gpio_recovery_info;
                 adap->bus_recovery_info->scl_gpio = dev->pdata->scl_pin;
                 adap->bus_recovery_info->sda_gpio = dev->pdata->sda_pin;