[media] mt2060: add param to split long i2c writes

Add configuration parameter to split long i2c writes as some I2C
adapters cannot write 10 bytes used as a one go.

Signed-off-by: Antti Palosaari <[e-mail]>
Signed-off-by: Mauro Carvalho Chehab <[e-mail]>

drivers/media/tuners/mt2060.c

···
 // Writes a set of consecutive registers
 static int mt2060_writeregs(struct mt2060_priv *priv,u8 *buf, u8 len)
 {
+	int rem, val_len;
+	u8 xfer_buf[16];
 	struct i2c_msg msg = {
-		.addr = priv->cfg->i2c_address, .flags = 0, .buf = buf, .len = len
+		.addr = priv->cfg->i2c_address, .flags = 0, .buf = xfer_buf
 	};
-	if (i2c_transfer(priv->i2c, &msg, 1) != 1) {
-		printk(KERN_WARNING "mt2060 I2C write failed (len=%i)\n",(int)len);
-		return -EREMOTEIO;
+
+	for (rem = len - 1; rem > 0; rem -= priv->i2c_max_regs) {
+		val_len = min_t(int, rem, priv->i2c_max_regs);
+		msg.len = 1 + val_len;
+		xfer_buf[0] = buf[0] + len - 1 - rem;
+		memcpy(&xfer_buf[1], &buf[1 + len - 1 - rem], val_len);
+
+		if (i2c_transfer(priv->i2c, &msg, 1) != 1) {
+			printk(KERN_WARNING "mt2060 I2C write failed (len=%i)\n", val_len);
+			return -EREMOTEIO;
+		}
 	}
+
 	return 0;
 }
 
···
 	priv->cfg      = cfg;
 	priv->i2c      = i2c;
 	priv->if1_freq = if1;
+	priv->i2c_max_regs = ~0;
 
 	if (fe->ops.i2c_gate_ctrl)
 		fe->ops.i2c_gate_ctrl(fe, 1); /* open i2c_gate */
···
 	dev->i2c = client->adapter;
 	dev->if1_freq = pdata->if1 ? pdata->if1 : 1220;
 	dev->client = client;
+	dev->i2c_max_regs = pdata->i2c_write_max ? pdata->i2c_write_max - 1 : ~0;
 
 	ret = mt2060_readreg(dev, REG_PART_REV, &chip_id);
 	if (ret) {

drivers/media/tuners/mt2060.h

···
  * struct mt2060_platform_data - Platform data for the mt2060 driver
  * @clock_out: Clock output setting. 0 = off, 1 = CLK/4, 2 = CLK/2, 3 = CLK/1.
  * @if1: First IF used [MHz]. 0 defaults to 1220.
+ * @i2c_write_max: Maximum number of bytes I2C adapter can write at once.
+ *  0 defaults to maximum.
  * @dvb_frontend: DVB frontend.
  */
 
 struct mt2060_platform_data {
 	u8 clock_out;
 	u16 if1;
+	unsigned int i2c_write_max:5;
 	struct dvb_frontend *dvb_frontend;
 };
 

drivers/media/tuners/mt2060_priv.h

···
 	struct i2c_client *client;
 	struct mt2060_config config;
 
+	u8 i2c_max_regs;
 	u32 frequency;
 	u16 if1_freq;
 	u8  fmfreq;