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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2017-05-18 11:23:55 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-07-15 11:57:46 +0200
commit45424528a184f8d3b698268db4bb58eaa52cbd6f (patch)
tree390e08ba6bc7bbe75fa1d39f8c1b45a695d11e7c /drivers
parent79565741fce0e70e5b208125adf331f26839ad37 (diff)
pinctrl: mxs: atomically switch mux and drive strength config
commit da6c2addf66d7ff7d0b090d6267d4292f951e4e6 upstream. To set the mux mode of a pin two bits must be set. Up to now this is implemented using the following idiom: writel(mask, reg + CLR); writel(value, reg + SET); . This however results in the mux mode being 0 between the two writes. On my machine there is an IC's reset pin connected to LCD_D20. The bootloader configures this pin as GPIO output-high (i.e. not holding the IC in reset). When Linux reconfigures the pin to GPIO the short time LCD_D20 is muxed as LCD_D20 instead of GPIO_1_20 is enough to confuse the connected IC. The same problem is present for the pin's drive strength setting which is reset to low drive strength before using the right value. So instead of relying on the hardware to modify the register setting using two writes implement the bit toggling using read-modify-write. Fixes: 17723111e64f ("pinctrl: add pinctrl-mxs support") Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Acked-by: Shawn Guo <shawnguo@kernel.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/pinctrl/freescale/pinctrl-mxs.c16
1 files changed, 12 insertions, 4 deletions
diff --git a/drivers/pinctrl/freescale/pinctrl-mxs.c b/drivers/pinctrl/freescale/pinctrl-mxs.c
index 6bbda6b4ab50..5da9c95dccb7 100644
--- a/drivers/pinctrl/freescale/pinctrl-mxs.c
+++ b/drivers/pinctrl/freescale/pinctrl-mxs.c
@@ -195,6 +195,16 @@ static int mxs_pinctrl_get_func_groups(struct pinctrl_dev *pctldev,
return 0;
}
+static void mxs_pinctrl_rmwl(u32 value, u32 mask, u8 shift, void __iomem *reg)
+{
+ u32 tmp;
+
+ tmp = readl(reg);
+ tmp &= ~(mask << shift);
+ tmp |= value << shift;
+ writel(tmp, reg);
+}
+
static int mxs_pinctrl_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
unsigned group)
{
@@ -212,8 +222,7 @@ static int mxs_pinctrl_set_mux(struct pinctrl_dev *pctldev, unsigned selector,
reg += bank * 0x20 + pin / 16 * 0x10;
shift = pin % 16 * 2;
- writel(0x3 << shift, reg + CLR);
- writel(g->muxsel[i] << shift, reg + SET);
+ mxs_pinctrl_rmwl(g->muxsel[i], 0x3, shift, reg);
}
return 0;
@@ -280,8 +289,7 @@ static int mxs_pinconf_group_set(struct pinctrl_dev *pctldev,
/* mA */
if (config & MA_PRESENT) {
shift = pin % 8 * 4;
- writel(0x3 << shift, reg + CLR);
- writel(ma << shift, reg + SET);
+ mxs_pinctrl_rmwl(ma, 0x3, shift, reg);
}
/* vol */