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atmel_flexcom: Support resuming after a chip reset 

The controller used by a flexcom module is configured at boot, and left
alone after this. In the suspend mode called "backup with self-refresh"
available on SAMA5D2, the chip will resume with most of its registers
reset. In this case, we need to restore the state of the flexcom driver
on resume.

Signed-off-by: Romain Izard <romain.izard.pro@gmail.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Tested-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
This commit is contained in:
Romain Izard 2017-12-12 17:21:19 +01:00 committed by Lee Jones
parent 63fb9cb51d
commit 7fdec11015
1 changed files with 48 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
drivers/mfd/atmel-flexcom.c
View File

@ -39,34 +39,43 @@
#define FLEX_MR_OPMODE(opmode) (((opmode) << FLEX_MR_OPMODE_OFFSET) & \
FLEX_MR_OPMODE_MASK)
struct atmel_flexcom {
void __iomem *base;
u32 opmode;
struct clk *clk;
};
static int atmel_flexcom_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct clk *clk;
struct resource *res;
void __iomem *base;
u32 opmode;
struct atmel_flexcom *ddata;
int err;
err = of_property_read_u32(np, "atmel,flexcom-mode", &opmode);
ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
platform_set_drvdata(pdev, ddata);
err = of_property_read_u32(np, "atmel,flexcom-mode", &ddata->opmode);
if (err)
return err;
if (opmode < ATMEL_FLEXCOM_MODE_USART ||
opmode > ATMEL_FLEXCOM_MODE_TWI)
if (ddata->opmode < ATMEL_FLEXCOM_MODE_USART ||
ddata->opmode > ATMEL_FLEXCOM_MODE_TWI)
return -EINVAL;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(base))
return PTR_ERR(base);
ddata->base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(ddata->base))
return PTR_ERR(ddata->base);
clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(clk))
return PTR_ERR(clk);
ddata->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(ddata->clk))
return PTR_ERR(ddata->clk);
err = clk_prepare_enable(clk);
err = clk_prepare_enable(ddata->clk);
if (err)
return err;
@ -76,9 +85,9 @@ static int atmel_flexcom_probe(struct platform_device *pdev)
* inaccessible and are read as zero. Also the external I/O lines of the
* Flexcom are muxed to reach the selected device.
*/
writel(FLEX_MR_OPMODE(opmode), base + FLEX_MR);
writel(FLEX_MR_OPMODE(ddata->opmode), ddata->base + FLEX_MR);
clk_disable_unprepare(clk);
clk_disable_unprepare(ddata->clk);
return devm_of_platform_populate(&pdev->dev);
}
@ -89,10 +98,34 @@ static const struct of_device_id atmel_flexcom_of_match[] = {
};
MODULE_DEVICE_TABLE(of, atmel_flexcom_of_match);
#ifdef CONFIG_PM_SLEEP
static int atmel_flexcom_resume(struct device *dev)
{
struct atmel_flexcom *ddata = dev_get_drvdata(dev);
int err;
u32 val;
err = clk_prepare_enable(ddata->clk);
if (err)
return err;
val = FLEX_MR_OPMODE(ddata->opmode),
writel(val, ddata->base + FLEX_MR);
clk_disable_unprepare(ddata->clk);
return 0;
}
#endif
static SIMPLE_DEV_PM_OPS(atmel_flexcom_pm_ops, NULL,
atmel_flexcom_resume);
static struct platform_driver atmel_flexcom_driver = {
.probe = atmel_flexcom_probe,
.driver = {
.name = "atmel_flexcom",
.pm = &atmel_flexcom_pm_ops,
.of_match_table = atmel_flexcom_of_match,
},
};