[PATCH] MPC52xxx I2C: make algo use of I2C_RSTA

[Bertrand BAUDET <bbaudet@lacie.com>]

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This patch makes use of I2C RESTART sequence when sending severals i2c_msg
instead of the STOP and START sequence.

Some I2C component reset there internal values when a STOP is sent.
(like the Ricoh rs5c372b I2C RTC)

Patch is against DENX linuxppc CVS

Regards,
Bertrand

[-- Attachment #2: mpc52xx_i2c-algo.patch --]
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--- linuxppc_2_4_devel_new/drivers/i2c/i2c-algo-mpc5xxx.c	2004-05-08 18:49:39.000000000 +0200
+++ linuxppc_2_4_devel-lacie6/drivers/i2c/i2c-algo-mpc5xxx.c	2004-12-13 15:53:37.000000000 +0100
@@ -62,6 +62,14 @@
 	return;
 }
 
+static void i2c_restart(struct i2c_algo_mpc5xxx_data *algo_data)
+{
+	struct mpc5xxx_i2c *regs = algo_data->regs;
+
+	mpc5xxx_out(&regs->mcr, MPC5xxx_I2C_RSTA, MPC5xxx_I2C_RSTA);
+
+	return;
+}
 
 static void i2c_stop(struct i2c_algo_mpc5xxx_data *algo_data)
 {
@@ -311,13 +319,14 @@
 	int				status;
 	int				i;
 
+	if (wait_for_bb(algo_data))
+		return -EREMOTEIO;
+	
+	i2c_start(algo_data);
+	
 	for (i = 0; i < num; i++) {
 		pmsg = &msgs[i];
 
-		if (wait_for_bb(algo_data))
-			return -EREMOTEIO;
-
-		i2c_start(algo_data);
   		mpc5xxx_do_address(algo_data, pmsg, adap->retries);
 
 		if (wait_for_pin(algo_data, &status)) {
@@ -332,17 +341,21 @@
 
 		if (pmsg->flags & I2C_M_RD) {
 			ret = mpc5xxx_readbytes(adap, pmsg->buf, pmsg->len);
-			if (ret != pmsg->len)
+			if (ret != pmsg->len) {
+				i2c_stop(algo_data);
 				return (ret < 0) ? ret : -EREMOTEIO;
+			}
 		} else {
 			ret = mpc5xxx_sendbytes(adap, pmsg->buf, pmsg->len);
-			if (ret != pmsg->len)
+			if (ret != pmsg->len) {
+				i2c_stop(algo_data);
 				return (ret < 0) ? ret : -EREMOTEIO;
+			}
 		}
-
-		i2c_stop(algo_data);
+		if (i+1 < num) i2c_restart(algo_data);
 	}
-
+	
+	i2c_stop(algo_data);
 	return num;
 }