i2c-mpc: avoid I2C abnormal after resuming from deep sleep

When entering deep sleep, the value in the registers I2CFDR and
I2CDFSRR are lost. This causes I2C access to fail after resuming.

Add suspend/resume routines to save/restore the registers
I2CFDR and I2CDFSRR.

Signed-off-by: Zhao Chenhui <chenhui.zhao@freescale.com>
Signed-off-by: Li Yang <leoli@freescale.com>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

drivers/i2c/busses/i2c-mpc.c

@@ -64,6 +64,9 @@ struct mpc_i2c {
 	struct i2c_adapter adap;
 	int irq;
 	u32 real_clk;
+#ifdef CONFIG_PM
+	u8 fdr, dfsrr;
+#endif
 };
 
 struct mpc_i2c_divider {
@@ -703,6 +706,30 @@ static int __devexit fsl_i2c_remove(struct platform_device *op)
 	return 0;
 };
 
+#ifdef CONFIG_PM
+static int mpc_i2c_suspend(struct device *dev)
+{
+	struct mpc_i2c *i2c = dev_get_drvdata(dev);
+
+	i2c->fdr = readb(i2c->base + MPC_I2C_FDR);
+	i2c->dfsrr = readb(i2c->base + MPC_I2C_DFSRR);
+
+	return 0;
+}
+
+static int mpc_i2c_resume(struct device *dev)
+{
+	struct mpc_i2c *i2c = dev_get_drvdata(dev);
+
+	writeb(i2c->fdr, i2c->base + MPC_I2C_FDR);
+	writeb(i2c->dfsrr, i2c->base + MPC_I2C_DFSRR);
+
+	return 0;
+}
+
+SIMPLE_DEV_PM_OPS(mpc_i2c_pm_ops, mpc_i2c_suspend, mpc_i2c_resume);
+#endif
+
 static struct mpc_i2c_data mpc_i2c_data_512x __devinitdata = {
 	.setup = mpc_i2c_setup_512x,
 };
@@ -747,6 +774,9 @@ static struct platform_driver mpc_i2c_driver = {
 		.owner = THIS_MODULE,
 		.name = DRV_NAME,
 		.of_match_table = mpc_i2c_of_match,
+#ifdef CONFIG_PM
+		.pm = &mpc_i2c_pm_ops,
+#endif
 	},
 };