[media] smiapp: Quirk for sensors that only do 8-bit reads

Some sensors implement only 8-bit read functionality and fail on wider
reads. Add a quirk flag for such sensors.

Signed-off-by: Sakari Ailus <sakari.ailus@maxwell.research.nokia.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

3 files changed, 66 insertions, 9 deletions

diff --git a/drivers/media/video/smiapp/smiapp-quirk.h b/drivers/media/video/smiapp/smiapp-quirk.h
index 7a1b3a02a7bd..de82cdf43a89 100644
--- a/drivers/media/video/smiapp/smiapp-quirk.h
+++ b/drivers/media/video/smiapp/smiapp-quirk.h
@@ -46,6 +46,7 @@ struct smiapp_quirk {
 
 /* op pix clock is for all lanes in total normally */
 #define SMIAPP_QUIRK_FLAG_OP_PIX_CLOCK_PER_LANE                 (1 << 0)
+#define SMIAPP_QUIRK_FLAG_8BIT_READ_ONLY                        (1 << 1)
 
 struct smiapp_reg_8 {
         u16 reg;
diff --git a/drivers/media/video/smiapp/smiapp-regs.c b/drivers/media/video/smiapp/smiapp-regs.c
index e5e5f4356dd2..9c430647b047 100644
--- a/drivers/media/video/smiapp/smiapp-regs.c
+++ b/drivers/media/video/smiapp/smiapp-regs.c
@@ -78,19 +78,15 @@ static uint32_t float_to_u32_mul_1000000(struct i2c_client *client,
  * Read a 8/16/32-bit i2c register.  The value is returned in 'val'.
  * Returns zero if successful, or non-zero otherwise.
  */
-int smiapp_read(struct smiapp_sensor *sensor, u32 reg, u32 *val)
+static int ____smiapp_read(struct smiapp_sensor *sensor, u16 reg,
+                           u16 len, u32 *val)
 {
         struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
         struct i2c_msg msg;
         unsigned char data[4];
-        unsigned int len = (u8)(reg >> 16);
         u16 offset = reg;
         int r;
 
-        if (len != SMIA_REG_8BIT && len != SMIA_REG_16BIT
-            && len != SMIA_REG_32BIT)
-                return -EINVAL;
-
         msg.addr = client->addr;
         msg.flags = 0;
         msg.len = 2;
@@ -132,9 +128,6 @@ int smiapp_read(struct smiapp_sensor *sensor, u32 reg, u32 *val)
                 BUG();
         }
 
-        if (reg & SMIA_REG_FLAG_FLOAT)
-                *val = float_to_u32_mul_1000000(client, *val);
-
         return 0;
 
 err:
@@ -143,6 +136,68 @@ err:
         return r;
 }
 
+/* Read a register using 8-bit access only. */
+static int ____smiapp_read_8only(struct smiapp_sensor *sensor, u16 reg,
+                                 u16 len, u32 *val)
+{
+        unsigned int i;
+        int rval;
+
+        *val = 0;
+
+        for (i = 0; i < len; i++) {
+                u32 val8;
+
+                rval = ____smiapp_read(sensor, reg + i, 1, &val8);
+                if (rval < 0)
+                        return rval;
+                *val |= val8 << ((len - i - 1) << 3);
+        }
+
+        return 0;
+}
+
+/*
+ * Read a 8/16/32-bit i2c register.  The value is returned in 'val'.
+ * Returns zero if successful, or non-zero otherwise.
+ */
+static int __smiapp_read(struct smiapp_sensor *sensor, u32 reg, u32 *val,
+                         bool only8)
+{
+        struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
+        unsigned int len = (u8)(reg >> 16);
+        int rval;
+
+        if (len != SMIA_REG_8BIT && len != SMIA_REG_16BIT
+            && len != SMIA_REG_32BIT)
+                return -EINVAL;
+
+        if (len == SMIA_REG_8BIT && !only8)
+                rval = ____smiapp_read(sensor, (u16)reg, len, val);
+        else
+                rval = ____smiapp_read_8only(sensor, (u16)reg, len, val);
+        if (rval < 0)
+                return rval;
+
+        if (reg & SMIA_REG_FLAG_FLOAT)
+                *val = float_to_u32_mul_1000000(client, *val);
+
+        return 0;
+}
+
+int smiapp_read(struct smiapp_sensor *sensor, u32 reg, u32 *val)
+{
+        return __smiapp_read(
+                sensor, reg, val,
+                smiapp_needs_quirk(sensor,
+                                   SMIAPP_QUIRK_FLAG_8BIT_READ_ONLY));
+}
+
+int smiapp_read_8only(struct smiapp_sensor *sensor, u32 reg, u32 *val)
+{
+        return __smiapp_read(sensor, reg, val, true);
+}
+
 /*
  * Write to a 8/16-bit register.
  * Returns zero if successful, or non-zero otherwise.
diff --git a/drivers/media/video/smiapp/smiapp-regs.h b/drivers/media/video/smiapp/smiapp-regs.h
index 1edfd206fb76..7f9013b47971 100644
--- a/drivers/media/video/smiapp/smiapp-regs.h
+++ b/drivers/media/video/smiapp/smiapp-regs.h
@@ -43,6 +43,7 @@ struct smia_reg {
 struct smiapp_sensor;
 
 int smiapp_read(struct smiapp_sensor *sensor, u32 reg, u32 *val);
+int smiapp_read_8only(struct smiapp_sensor *sensor, u32 reg, u32 *val);
 int smiapp_write(struct smiapp_sensor *sensor, u32 reg, u32 val);
 
 #endif