[media] cx24116: add config option to split firmware download

It is very rare I2C adapter hardware which can provide 32kB I2C write
as one write. Add .i2c_wr_max option to set desired max packet size.
Split transaction to smaller pieces according to that option.

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

drivers/media/dvb/frontends/cx24116.c

···
 {
 	struct cx24116_state *state = fe->demodulator_priv;
 	struct cx24116_cmd cmd;
-	int i, ret;
+	int i, ret, len, remaining;
 	unsigned char vers[4];
 
 	dprintk("%s\n", __func__);
···
 	cx24116_writereg(state, 0xF5, 0x00);
 	cx24116_writereg(state, 0xF6, 0x00);
 
-	/* write the entire firmware as one transaction */
-	cx24116_writeregN(state, 0xF7, fw->data, fw->size);
+	/* Split firmware to the max I2C write len and write.
+	 * This overflows 16 bit intentionally in order to get max write
+	 * len when i2c_wr_max is set to 0. */
+	for (remaining = fw->size; remaining > 0;
+		remaining -= (u16) (state->config->i2c_wr_max - 1)) {
+
+		len = remaining;
+		if (len > (u16) (state->config->i2c_wr_max - 1))
+			len = (u16) (state->config->i2c_wr_max - 1);
+
+		cx24116_writeregN(state, 0xF7, &fw->data[fw->size - remaining],
+			len);
+	}
 
 	cx24116_writereg(state, 0xF4, 0x10);
 	cx24116_writereg(state, 0xF0, 0x00);

drivers/media/dvb/frontends/cx24116.h

···
 
 	/* Need to set MPEG parameters */
 	u8 mpg_clk_pos_pol:0x02;
+
+	/* max bytes I2C provider can write at once */
+	u16 i2c_wr_max;
 };
 
 #if defined(CONFIG_DVB_CX24116) || \