[PATCH v2] i2c-mpc: avoid I2C abnormal after resuming from deep sleep

[PATCH v2] i2c-mpc: avoid I2C abnormal after resuming from deep sleep

[Zhao Chenhui]

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-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
Signed-off-by: Li Yang <leoli-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
 drivers/i2c/busses/i2c-mpc.c |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index a8ebb84..fb2627b 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/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 {
@@ -668,6 +671,30 @@ 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,
 };
@@ -712,6 +739,9 @@ 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
 	},
 };
 
-- 
1.6.4.1

Re: [PATCH v2] i2c-mpc: avoid I2C abnormal after resuming from deep sleep

[Wolfram Sang]

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On Thu, Apr 19, 2012 at 05:51:34PM +0800, Zhao Chenhui wrote:

> 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-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
> Signed-off-by: Li Yang <leoli-KZfg59tc24xl57MIdRCFDg@public.gmane.org>

Applied to next. Thanks!

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

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