6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Matthias Schiffer matthias.schiffer@ew.tq-group.com
[ Upstream commit 9d6a811b522ba558bcb4ec01d12e72a0af8e9f6e ]
The TQMx86 GPIO controller uses the same register address for input and output data. Reading the register will always return current inputs rather than the previously set outputs (regardless of the current direction setting). Therefore, using a RMW pattern does not make sense when setting output values. Instead, the previously set output register value needs to be stored as a shadow register.
As there is no reliable way to get the current output values from the hardware, also initialize all channels to 0, to ensure that stored and actual output values match. This should usually not have any effect in practise, as the TQMx86 UEFI sets all outputs to 0 during boot.
Also prepare for extension of the driver to more than 8 GPIOs by using DECLARE_BITMAP.
Fixes: b868db94a6a7 ("gpio: tqmx86: Add GPIO from for this IO controller") Signed-off-by: Matthias Schiffer matthias.schiffer@ew.tq-group.com Reviewed-by: Andrew Lunn andrew@lunn.ch Link: https://lore.kernel.org/r/d0555933becd45fa92a85675d26e4d59343ddc01.171706399... Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpio/gpio-tqmx86.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-)
diff --git a/drivers/gpio/gpio-tqmx86.c b/drivers/gpio/gpio-tqmx86.c index f0a2cf4b06796..da689b5b3fad2 100644 --- a/drivers/gpio/gpio-tqmx86.c +++ b/drivers/gpio/gpio-tqmx86.c @@ -6,6 +6,7 @@ * Vadim V.Vlasov vvlasov@dev.rtsoft.ru */
+#include <linux/bitmap.h> #include <linux/bitops.h> #include <linux/errno.h> #include <linux/gpio/driver.h> @@ -38,6 +39,7 @@ struct tqmx86_gpio_data { void __iomem *io_base; int irq; raw_spinlock_t spinlock; + DECLARE_BITMAP(output, TQMX86_NGPIO); u8 irq_type[TQMX86_NGPI]; };
@@ -64,15 +66,10 @@ static void tqmx86_gpio_set(struct gpio_chip *chip, unsigned int offset, { struct tqmx86_gpio_data *gpio = gpiochip_get_data(chip); unsigned long flags; - u8 val;
raw_spin_lock_irqsave(&gpio->spinlock, flags); - val = tqmx86_gpio_read(gpio, TQMX86_GPIOD); - if (value) - val |= BIT(offset); - else - val &= ~BIT(offset); - tqmx86_gpio_write(gpio, val, TQMX86_GPIOD); + __assign_bit(offset, gpio->output, value); + tqmx86_gpio_write(gpio, bitmap_get_value8(gpio->output, 0), TQMX86_GPIOD); raw_spin_unlock_irqrestore(&gpio->spinlock, flags); }
@@ -259,6 +256,13 @@ static int tqmx86_gpio_probe(struct platform_device *pdev)
tqmx86_gpio_write(gpio, (u8)~TQMX86_DIR_INPUT_MASK, TQMX86_GPIODD);
+ /* + * Reading the previous output state is not possible with TQMx86 hardware. + * Initialize all outputs to 0 to have a defined state that matches the + * shadow register. + */ + tqmx86_gpio_write(gpio, 0, TQMX86_GPIOD); + chip = &gpio->chip; chip->label = "gpio-tqmx86"; chip->owner = THIS_MODULE;