gpio/nomadik: support low EMI mode
Low EMI (Electro-Magnetic Interference) mode means lower slew
rate on the signals. The Nomadik GPIO controller supports
this so create an interface to enable it.
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Reviewed-by: Srinidhi Kasagar <srinidhi.kasagar@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
diff --git a/drivers/gpio/gpio-nomadik.c b/drivers/gpio/gpio-nomadik.c
index 681daee8..7b45d88 100644
--- a/drivers/gpio/gpio-nomadik.c
+++ b/drivers/gpio/gpio-nomadik.c
@@ -61,6 +61,7 @@
u32 rimsc;
u32 fimsc;
u32 pull_up;
+ u32 lowemi;
};
static struct nmk_gpio_chip *
@@ -125,6 +126,24 @@
}
}
+static void __nmk_gpio_set_lowemi(struct nmk_gpio_chip *nmk_chip,
+ unsigned offset, bool lowemi)
+{
+ u32 bit = BIT(offset);
+ bool enabled = nmk_chip->lowemi & bit;
+
+ if (lowemi == enabled)
+ return;
+
+ if (lowemi)
+ nmk_chip->lowemi |= bit;
+ else
+ nmk_chip->lowemi &= ~bit;
+
+ writel_relaxed(nmk_chip->lowemi,
+ nmk_chip->addr + NMK_GPIO_LOWEMI);
+}
+
static void __nmk_gpio_make_input(struct nmk_gpio_chip *nmk_chip,
unsigned offset)
{
@@ -269,6 +288,8 @@
__nmk_gpio_set_pull(nmk_chip, offset, pull);
}
+ __nmk_gpio_set_lowemi(nmk_chip, offset, PIN_LOWEMI(cfg));
+
/*
* If the pin is switching to altfunc, and there was an interrupt
* installed on it which has been lazy disabled, actually mask the
@@ -1181,6 +1202,10 @@
chip->dev = &dev->dev;
chip->owner = THIS_MODULE;
+ clk_enable(nmk_chip->clk);
+ nmk_chip->lowemi = readl_relaxed(nmk_chip->addr + NMK_GPIO_LOWEMI);
+ clk_disable(nmk_chip->clk);
+
ret = gpiochip_add(&nmk_chip->chip);
if (ret)
goto out_free;