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

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Message-ID: <1330511961-22498-1-git-send-email-chenhui.zhao@freescale.com>
Date:	Wed, 29 Feb 2012 18:39:21 +0800
From:	Zhao Chenhui <chenhui.zhao@...escale.com>
To:	<linux-i2c@...r.kernel.org>
CC:	<linux-kernel@...r.kernel.org>,
	Zhao Chenhui <chenhui.zhao@...escale.com>,
	Li Yang <leoli@...escale.com>
Subject: [PATCH] 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@...escale.com>
Signed-off-by: Li Yang <leoli@...escale.com>
---
 drivers/i2c/busses/i2c-mpc.c |   34 +++++++++++++++++++++++++++++++++-
 1 files changed, 33 insertions(+), 1 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mpc.c b/drivers/i2c/busses/i2c-mpc.c
index a8ebb84..f95a647 100644
--- a/drivers/i2c/busses/i2c-mpc.c
+++ b/drivers/i2c/busses/i2c-mpc.c
@@ -1,7 +1,9 @@
 /*
  * (C) Copyright 2003-2004
  * Humboldt Solutions Ltd, adrian@...boldt.co.uk.
-
+ *
+ * Copyright 2012 Freescale Semiconductor, Inc.
+ *
  * This is a combined i2c adapter and algorithm driver for the
  * MPC107/Tsi107 PowerPC northbridge and processors that include
  * the same I2C unit (8240, 8245, 85xx).
@@ -64,6 +66,9 @@ 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 +673,30 @@ 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 +741,9 @@ 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


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