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gpio: mmio: Support two direction registers

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It turns out that one specific hardware has two direction
registers: one to set a GPIO line as input and another one
to set a GPIO line as output. So in theory a line can be
configured as input and output at the same time.

Make the MMIO GPIO helper deal with this: store both
registers in the state container, use both in the generic
code if present. Synchronize the input register to the
output register when we register a GPIO chip, with the
output settings taking precedence.

Keep the helper variable to detect inverted direction
semantics (only direction in register) but augment the
code to be more straight-forward for the generic case
when setting the registers.

Fix some flunky with unreadable direction registers at
the same time as we're touching this code.

Cc: David Woods <dwoods@mellanox.com>
Cc: Shravan Kumar Ramani <sramani@mellanox.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij
2019-02-22 11:14:44 +01:00
parent 9e98c678c2
commit f69e00bd21
2 changed files with 67 additions and 33 deletions
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15
include/linux/gpio/driver.h
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@@ -227,9 +227,13 @@ struct gpio_irq_chip {
* @reg_dat: data (in) register for generic GPIO
* @reg_set: output set register (out=high) for generic GPIO
* @reg_clr: output clear register (out=low) for generic GPIO
* @reg_dir: direction setting register for generic GPIO
* @reg_dir_out: direction out setting register for generic GPIO
* @reg_dir_in: direction in setting register for generic GPIO
* @bgpio_dir_inverted: indicates that the direction register is inverted
* (gpiolib private state variable)
* (gpiolib private state variable) this means @reg_dir_in is
* available but not @reg_dir_out.
* @bgpio_dir_unreadable: indicates that the direction register(s) cannot
* be read and we need to rely on out internal state tracking.
* @bgpio_bits: number of register bits used for a generic GPIO i.e.
* <register width> * 8
* @bgpio_lock: used to lock chip->bgpio_data. Also, this is needed to keep
@@ -237,7 +241,8 @@ struct gpio_irq_chip {
* @bgpio_data: shadowed data register for generic GPIO to clear/set bits
* safely.
* @bgpio_dir: shadowed direction register for generic GPIO to clear/set
* direction safely.
* direction safely. A "1" in this word means the line is set as
* output.
*
* A gpio_chip can help platforms abstract various sources of GPIOs so
* they can all be accessed through a common programing interface.
@@ -298,8 +303,10 @@ struct gpio_chip {
void __iomem *reg_dat;
void __iomem *reg_set;
void __iomem *reg_clr;
void __iomem *reg_dir;
void __iomem *reg_dir_out;
void __iomem *reg_dir_in;
bool bgpio_dir_inverted;
bool bgpio_dir_unreadable;
int bgpio_bits;
spinlock_t bgpio_lock;
unsigned long bgpio_data;