[PATCH v2 2/2] gpio: mmio: Use new flag BGPIOF_NO_INPUT.

Niall Leonard via B4 Submission Endpoint
2023-01-31T13:49:55Z

From: Niall Leonard <nl250060@ncr.com>

Add new flag BGPIOF_NO_INPUT to header file.
Use the existing shadow data register 'bgpio_data' to allow
the last written value to be returned by the read operation
when BGPIOF_NO_INPUT flag is set.
Ensure this change only applies to the specific binding "wd,mbl-gpio".

Signed-off-by: Niall Leonard <nl250060@ncr.com>
---
drivers/gpio/gpio-mmio.c | 24 +++++++++++++++++++++---
include/linux/gpio/driver.h | 1 +
2 files changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/gpio/gpio-mmio.c b/drivers/gpio/gpio-mmio.c
index d9dff3dc92ae..9939fdbf6345 100644
--- a/drivers/gpio/gpio-mmio.c
+++ b/drivers/gpio/gpio-mmio.c
@@ -164,6 +164,11 @@ static int bgpio_get_set_multiple(struct gpio_chip *gc, unsigned long *mask,
return 0;
}

+static int bgpio_get_shadow(struct gpio_chip *gc, unsigned int gpio)
+{
+ return !!(gc->bgpio_data & bgpio_line2mask(gc, gpio));
+}
+
static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
{
return !!(gc->read_reg(gc->reg_dat) & bgpio_line2mask(gc, gpio));
@@ -526,7 +531,10 @@ static int bgpio_setup_io(struct gpio_chip *gc,
* reading each line individually in that fringe case.
*/
} else {
- gc->get = bgpio_get;
+ if (flags & BGPIOF_NO_INPUT)
+ gc->get = bgpio_get_shadow;
+ else
+ gc->get = bgpio_get;
if (gc->be_bits)
gc->get_multiple = bgpio_get_multiple_be;
else
@@ -630,7 +638,11 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
if (ret)
return ret;

- gc->bgpio_data = gc->read_reg(gc->reg_dat);
+ if (flags & BGPIOF_NO_INPUT)
+ gc->bgpio_data = 0;
+ else
+ gc->bgpio_data = gc->read_reg(gc->reg_dat);
+
if (gc->set == bgpio_set_set &&
!(flags & BGPIOF_UNREADABLE_REG_SET))
gc->bgpio_data = gc->read_reg(gc->reg_set);
@@ -694,8 +706,9 @@ static struct bgpio_pdata *bgpio_parse_dt(struct platform_device *pdev,
unsigned long *flags)
{
struct bgpio_pdata *pdata;
+ const struct of_device_id *of_id;

- if (!of_match_device(bgpio_of_match, &pdev->dev))
+ if (!(of_id = of_match_device(bgpio_of_match, &pdev->dev)))
return NULL;

pdata = devm_kzalloc(&pdev->dev, sizeof(struct bgpio_pdata),
@@ -711,6 +724,11 @@ static struct bgpio_pdata *bgpio_parse_dt(struct platform_device *pdev,
if (of_property_read_bool(pdev->dev.of_node, "no-output"))
*flags |= BGPIOF_NO_OUTPUT;

+ if (!strcmp(of_id->compatible, "wd,mbl-gpio")) {
+ if (of_property_read_bool(pdev->dev.of_node, "no-input"))
+ *flags |= BGPIOF_NO_INPUT;
+ }
+
return pdata;
}
#else
diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h
index 44783fc16125..e8e57310e3b8 100644
--- a/include/linux/gpio/driver.h
+++ b/include/linux/gpio/driver.h
@@ -682,6 +682,7 @@ int bgpio_init(struct gpio_chip *gc, struct device *dev,
#define BGPIOF_READ_OUTPUT_REG_SET BIT(4) /* reg_set stores output value */
#define BGPIOF_NO_OUTPUT BIT(5) /* only input */
#define BGPIOF_NO_SET_ON_INPUT BIT(6)
+#define BGPIOF_NO_INPUT BIT(7) /* only output */

int gpiochip_irq_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq);

--
2.34.1