drm/amdgpu: EEPROM respects I2C quirks

Consult the i2c_adapter.quirks table for
the maximum read/write data length per bus
transaction. Do not exceed this transaction
limit.

Cc: Jean Delvare <jdelvare@suse.de>
Cc: Alexander Deucher <Alexander.Deucher@amd.com>
Cc: Andrey Grodzovsky <Andrey.Grodzovsky@amd.com>
Cc: Lijo Lazar <Lijo.Lazar@amd.com>
Cc: Stanley Yang <Stanley.Yang@amd.com>
Cc: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Luben Tuikov <luben.tuikov@amd.com>
Acked-by: Alexander Deucher <Alexander.Deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
index 7fdb5bd..94aeda1 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_eeprom.c
@@ -32,20 +32,9 @@
 
 #define EEPROM_OFFSET_SIZE 2
 
-/**
- * amdgpu_eeprom_xfer -- Read/write from/to an I2C EEPROM device
- * @i2c_adap: pointer to the I2C adapter to use
- * @slave_addr: I2C address of the slave device
- * @eeprom_addr: EEPROM address from which to read/write
- * @eeprom_buf: pointer to data buffer to read into/write from
- * @buf_size: the size of @eeprom_buf
- * @read: True if reading from the EEPROM, false if writing
- *
- * Returns the number of bytes read/written; -errno on error.
- */
-int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
-                      u16 slave_addr, u16 eeprom_addr,
-                      u8 *eeprom_buf, u16 buf_size, bool read)
+static int __amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
+                               u16 slave_addr, u16 eeprom_addr,
+                               u8 *eeprom_buf, u16 buf_size, bool read)
 {
        u8 eeprom_offset_buf[EEPROM_OFFSET_SIZE];
        struct i2c_msg msgs[] = {
@@ -65,8 +54,8 @@ int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
        u16 len;
 
        r = 0;
-       for (len = 0; buf_size > 0;
-            buf_size -= len, eeprom_addr += len, eeprom_buf += len) {
+       for ( ; buf_size > 0;
+             buf_size -= len, eeprom_addr += len, eeprom_buf += len) {
                /* Set the EEPROM address we want to write to/read from.
                 */
                msgs[0].buf[0] = (eeprom_addr >> 8) & 0xff;
@@ -120,3 +109,62 @@ int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
 
        return r < 0 ? r : eeprom_buf - p;
 }
+
+/**
+ * amdgpu_eeprom_xfer -- Read/write from/to an I2C EEPROM device
+ * @i2c_adap: pointer to the I2C adapter to use
+ * @slave_addr: I2C address of the slave device
+ * @eeprom_addr: EEPROM address from which to read/write
+ * @eeprom_buf: pointer to data buffer to read into/write from
+ * @buf_size: the size of @eeprom_buf
+ * @read: True if reading from the EEPROM, false if writing
+ *
+ * Returns the number of bytes read/written; -errno on error.
+ */
+int amdgpu_eeprom_xfer(struct i2c_adapter *i2c_adap,
+                      u16 slave_addr, u16 eeprom_addr,
+                      u8 *eeprom_buf, u16 buf_size, bool read)
+{
+       const struct i2c_adapter_quirks *quirks = i2c_adap->quirks;
+       u16 limit;
+
+       if (!quirks)
+               limit = 0;
+       else if (read)
+               limit = quirks->max_read_len;
+       else
+               limit = quirks->max_write_len;
+
+       if (limit == 0) {
+               return __amdgpu_eeprom_xfer(i2c_adap, slave_addr, eeprom_addr,
+                                           eeprom_buf, buf_size, read);
+       } else if (limit <= EEPROM_OFFSET_SIZE) {
+               dev_err_ratelimited(&i2c_adap->dev,
+                                   "maddr:0x%04X size:0x%02X:quirk max_%s_len must be > %d",
+                                   eeprom_addr, buf_size,
+                                   read ? "read" : "write", EEPROM_OFFSET_SIZE);
+               return -EINVAL;
+       } else {
+               u16 ps; /* Partial size */
+               int res = 0, r;
+
+               /* The "limit" includes all data bytes sent/received,
+                * which would include the EEPROM_OFFSET_SIZE bytes.
+                * Account for them here.
+                */
+               limit -= EEPROM_OFFSET_SIZE;
+               for ( ; buf_size > 0;
+                     buf_size -= ps, eeprom_addr += ps, eeprom_buf += ps) {
+                       ps = min(limit, buf_size);
+
+                       r = __amdgpu_eeprom_xfer(i2c_adap,
+                                                slave_addr, eeprom_addr,
+                                                eeprom_buf, ps, read);
+                       if (r < 0)
+                               return r;
+                       res += r;
+               }
+
+               return res;
+       }
+}