Re: [PATCH] i2c-mpc: avoid I2C abnormal after resuming from deep sleep
From: Shubhrajyoti Datta
Date: Wed Feb 29 2012 - 08:02:07 EST
Hi Zhao,
On Wed, Feb 29, 2012 at 4:09 PM, Zhao Chenhui
<chenhui.zhao@xxxxxxxxxxxxx> 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@xxxxxxxxxxxxx>
> Signed-off-by: Li Yang <leoli@xxxxxxxxxxxxx>
> ---
> 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@xxxxxxxxxxxxxxx
> -
> + *
> + * 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;
How about having a structure here ?
> +#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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