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pinctrl: intel: Avoid potential glitches if pin is in GPIO mode 

When consumer requests a pin, in order to be on the safest side,
we switch it first to GPIO mode followed by immediate transition
to the input state. Due to posted writes it's luckily to be a single
I/O transaction.

However, if firmware or boot loader already configures the pin
to the GPIO mode, user expects no glitches for the requested pin.
We may check if the pin is pre-configured and leave it as is
till the actual consumer toggles its state to avoid glitches.

Fixes: 7981c0015a ("pinctrl: intel: Add Intel Sunrisepoint pin controller and GPIO support")
Depends-on: f5a26acf01 ("pinctrl: intel: Initialize GPIO properly when used through irqchip")
Cc: stable@vger.kernel.org
Cc: fei.yang@intel.com
Reported-by: Oliver Barta <oliver.barta@aptiv.com>
Reported-by: Malin Jonsson <malin.jonsson@ericsson.com>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
alistair/sunxi64-5.4-dsi
Andy Shevchenko 2019-10-14 12:51:04 +03:00 committed by Mika Westerberg
parent 260996c30f
commit 29c2c6aa32
1 changed files with 20 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/pinctrl/intel/pinctrl-intel.c
View File

@ -52,6 +52,7 @@
#define PADCFG0_GPIROUTNMI BIT(17)
#define PADCFG0_PMODE_SHIFT 10
#define PADCFG0_PMODE_MASK GENMASK(13, 10)
#define PADCFG0_PMODE_GPIO 0
#define PADCFG0_GPIORXDIS BIT(9)
#define PADCFG0_GPIOTXDIS BIT(8)
#define PADCFG0_GPIORXSTATE BIT(1)
@ -332,7 +333,7 @@ static void intel_pin_dbg_show(struct pinctrl_dev *pctldev, struct seq_file *s,
cfg1 = readl(intel_get_padcfg(pctrl, pin, PADCFG1));
mode = (cfg0 & PADCFG0_PMODE_MASK) >> PADCFG0_PMODE_SHIFT;
if (!mode)
if (mode == PADCFG0_PMODE_GPIO)
seq_puts(s, "GPIO ");
else
seq_printf(s, "mode %d ", mode);
@ -458,6 +459,11 @@ static void __intel_gpio_set_direction(void __iomem *padcfg0, bool input)
writel(value, padcfg0);
}
static int intel_gpio_get_gpio_mode(void __iomem *padcfg0)
{
return (readl(padcfg0) & PADCFG0_PMODE_MASK) >> PADCFG0_PMODE_SHIFT;
}
static void intel_gpio_set_gpio_mode(void __iomem *padcfg0)
{
u32 value;
@ -491,7 +497,20 @@ static int intel_gpio_request_enable(struct pinctrl_dev *pctldev,
}
padcfg0 = intel_get_padcfg(pctrl, pin, PADCFG0);
/*
* If pin is already configured in GPIO mode, we assume that
* firmware provides correct settings. In such case we avoid
* potential glitches on the pin. Otherwise, for the pin in
* alternative mode, consumer has to supply respective flags.
*/
if (intel_gpio_get_gpio_mode(padcfg0) == PADCFG0_PMODE_GPIO) {
raw_spin_unlock_irqrestore(&pctrl->lock, flags);
return 0;
}
intel_gpio_set_gpio_mode(padcfg0);
/* Disable TX buffer and enable RX (this will be input) */
__intel_gpio_set_direction(padcfg0, true);