media: i2c: Add support for 19.2MHz clock to ov7251

The OV7251 sensor is used as the IR camera sensor on the Microsoft
Surface line of tablets; this provides a 19.2MHz external clock. Add
the ability to support that rate to the driver by defining a new set
of PLL configs. Extend the clock handling in .probe() to check for
either supported frequency.

Signed-off-by: Daniel Scally <djrscally@gmail.com>

diff --git a/drivers/media/i2c/ov7251.c b/drivers/media/i2c/ov7251.c
index a7576f6..084d68b 100644 (file)
--- a/drivers/media/i2c/ov7251.c
+++ b/drivers/media/i2c/ov7251.c
@@ -134,10 +134,19 @@ static inline struct ov7251 *to_ov7251(struct v4l2_subdev *sd)
 }
 
 enum xclk_rate {
+       OV7251_19_2_MHZ,
        OV7251_24_MHZ,
        OV7251_NUM_SUPPORTED_RATES
 };
 
+static const struct ov7251_pll1_config ov7251_pll1_config_19_2_mhz = {
+       .pre_div = 0x03,
+       .mult = 0x4b,
+       .div = 0x01,
+       .pix_div = 0x0a,
+       .mipi_div = 0x05
+};
+
 static const struct ov7251_pll1_config ov7251_pll1_config_24_mhz = {
        .pre_div = 0x03,
        .mult = 0x64,
@@ -146,6 +155,14 @@ static const struct ov7251_pll1_config ov7251_pll1_config_24_mhz = {
        .mipi_div = 0x05
 };
 
+static const struct ov7251_pll2_config ov7251_pll2_config_19_2_mhz = {
+       .pre_div = 0x04,
+       .mult = 0x32,
+       .div = 0x00,
+       .sys_div = 0x05,
+       .adc_div = 0x04
+};
+
 static const struct ov7251_pll2_config ov7251_pll2_config_24_mhz = {
        .pre_div = 0x04,
        .mult = 0x28,
@@ -154,12 +171,18 @@ static const struct ov7251_pll2_config ov7251_pll2_config_24_mhz = {
        .adc_div = 0x04
 };
 
+static const struct ov7251_pll_configs ov7251_pll_configs_19_2_mhz = {
+       .pll1 = &ov7251_pll1_config_19_2_mhz,
+       .pll2 = &ov7251_pll2_config_19_2_mhz
+};
+
 static const struct ov7251_pll_configs ov7251_pll_configs_24_mhz = {
        .pll1 = &ov7251_pll1_config_24_mhz,
        .pll2 = &ov7251_pll2_config_24_mhz
 };
 
 static const struct ov7251_pll_configs *ov7251_pll_configs[] = {
+       [OV7251_19_2_MHZ] = &ov7251_pll_configs_19_2_mhz,
        [OV7251_24_MHZ] = &ov7251_pll_configs_24_mhz
 };
 
@@ -553,6 +576,7 @@ static const struct reg_value ov7251_setting_vga_90fps[] = {
 };
 
 static const unsigned long supported_xclk_rates[] = {
+       [OV7251_19_2_MHZ] = 19200000,
        [OV7251_24_MHZ] = 24000000,
 };
 
@@ -1424,6 +1448,7 @@ static int ov7251_probe(struct i2c_client *client)
        struct device *dev = &client->dev;
        struct ov7251 *ov7251;
        u8 chip_id_high, chip_id_low, chip_rev;
+       unsigned int rate = 0;
        int ret;
        int i;
 
@@ -1439,35 +1464,39 @@ static int ov7251_probe(struct i2c_client *client)
                return ret;
 
        /* get system clock (xclk) */
-       ov7251->xclk = devm_clk_get(dev, "xclk");
+       ov7251->xclk = devm_clk_get(dev, NULL);
        if (IS_ERR(ov7251->xclk)) {
                dev_err(dev, "could not get xclk");
                return PTR_ERR(ov7251->xclk);
        }
 
+       /*
+        * We could have either a 24MHz or 19.2MHz clock rate from either dt or
+        * ACPI. We also need to support the IPU3 case which will have both an
+        * external clock AND a clock-frequency property.
+        */
        ret = fwnode_property_read_u32(dev_fwnode(dev), "clock-frequency",
-                                      &ov7251->xclk_freq);
-       if (ret) {
-               dev_err(dev, "could not get xclk frequency\n");
-               return ret;
+                                      &rate);
+       if (!ret && ov7251->xclk) {
+               ret = clk_set_rate(ov7251->xclk, rate);
+               if (ret)
+                       return dev_err_probe(dev, ret,
+                                            "failed to set clock rate\n");
+       } else if (ret && !ov7251->xclk) {
+               return dev_err_probe(dev, ret, "invalid clock config\n");
        }
 
-       /* external clock must be 24MHz, allow 1% tolerance */
-       if (ov7251->xclk_freq < 23760000 || ov7251->xclk_freq > 24240000) {
-               dev_err(dev, "external clock frequency %u is not supported\n",
-                       ov7251->xclk_freq);
-               return -EINVAL;
-       }
+       ov7251->xclk_freq = rate ? rate : clk_get_rate(ov7251->xclk);
 
-       ret = clk_set_rate(ov7251->xclk, ov7251->xclk_freq);
-       if (ret) {
-               dev_err(dev, "could not set xclk frequency\n");
-               return ret;
-       }
        for (i = 0; i < ARRAY_SIZE(supported_xclk_rates); i++)
                if (ov7251->xclk_freq == supported_xclk_rates[i])
                        break;
 
+       if (i == ARRAY_SIZE(supported_xclk_rates))
+               return dev_err_probe(dev, -EINVAL,
+                                    "clock rate %u Hz is unsupported\n",
+                                    ov7251->xclk_freq);
+
        ov7251->pll_configs = ov7251_pll_configs[i];
 
        ov7251->io_regulator = devm_regulator_get(dev, "vdddo");