[PATCH V4 4/4] gpio: tegra: Add support for gpio debounce

Laxman Dewangan
2016-04-22T10:21:23Z

NVIDIA's Tegra210 support the HW debounce in the GPIO controller
for all its GPIO pins.

Add support for setting debounce timing by implementing the
set_debounce callback of gpiochip.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>

---
Changes from V1:
- Write debounce count before enable.
- Make sure the debounce count do not have any boot residuals.

Changes from V2:
- Only access register for debounce when SoC support debounce.

Changes from V3:
- Add locking mechanism in debounce count register update.
- Move DBC register from prev patch to here.

drivers/gpio/gpio-tegra.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 68 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-tegra.c b/drivers/gpio/gpio-tegra.c
index 6af5eb2..45d80ec 100644
--- a/drivers/gpio/gpio-tegra.c
+++ b/drivers/gpio/gpio-tegra.c
@@ -46,10 +46,13 @@
#define GPIO_INT_ENB(t, x) (GPIO_REG(t, x) + 0x50)
#define GPIO_INT_LVL(t, x) (GPIO_REG(t, x) + 0x60)
#define GPIO_INT_CLR(t, x) (GPIO_REG(t, x) + 0x70)
+#define GPIO_DBC_CNT(t, x) (GPIO_REG(t, x) + 0xF0)
+

#define GPIO_MSK_CNF(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x00)
#define GPIO_MSK_OE(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x10)
#define GPIO_MSK_OUT(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0X20)
+#define GPIO_MSK_DBC_EN(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x30)
#define GPIO_MSK_INT_STA(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x40)
#define GPIO_MSK_INT_ENB(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x50)
#define GPIO_MSK_INT_LVL(t, x) (GPIO_REG(t, x) + t->soc->upper_offset + 0x60)
@@ -67,6 +70,7 @@ struct tegra_gpio_bank {
int bank;
int irq;
spinlock_t lvl_lock[4];
+ spinlock_t dbc_lock[4]; /* Lock for updating debounce count register */
#ifdef CONFIG_PM_SLEEP
u32 cnf[4];
u32 out[4];
@@ -74,11 +78,14 @@ struct tegra_gpio_bank {
u32 int_enb[4];
u32 int_lvl[4];
u32 wake_enb[4];
+ u32 dbc_enb[4];
#endif
+ u32 dbc_cnt[4];
struct tegra_gpio_info *tgi;
};

struct tegra_gpio_soc_config {
+ bool debounce_supported;
u32 bank_stride;
u32 upper_offset;
};
@@ -182,6 +189,38 @@ static int tegra_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
return 0;
}

+static int tegra_gpio_set_debounce(struct gpio_chip *chip, unsigned int offset,
+ unsigned int debounce)
+{
+ struct tegra_gpio_info *tgi = gpiochip_get_data(chip);
+ unsigned int debounce_ms = DIV_ROUND_UP(debounce, 1000);
+ unsigned long flags;
+ int port = GPIO_PORT(offset);
+ int bank = GPIO_BANK(offset);
+
+ if (!debounce_ms) {
+ tegra_gpio_mask_write(tgi, GPIO_MSK_DBC_EN(tgi, offset),
+ offset, 0);
+ return 0;
+ }
+
+ debounce_ms = min(debounce_ms, 255U);
+
+ /* There is only one debounce count register per port and hence
+ * set the maximum of current and requested debounce time.
+ */
+ spin_lock_irqsave(&tgi->bank_info[bank].dbc_lock[port], flags);
+ if (tgi->bank_info[bank].dbc_cnt[port] < debounce_ms) {
+ tegra_gpio_writel(tgi, debounce_ms, GPIO_DBC_CNT(tgi, offset));
+ tgi->bank_info[bank].dbc_cnt[port] = debounce_ms;
+ }
+ spin_unlock_irqrestore(&tgi->bank_info[bank].dbc_lock[port], flags);
+
+ tegra_gpio_mask_write(tgi, GPIO_MSK_DBC_EN(tgi, offset), offset, 1);
+
+ return 0;
+}
+
static int tegra_gpio_to_irq(struct gpio_chip *chip, unsigned offset)
{
struct tegra_gpio_info *tgi = gpiochip_get_data(chip);
@@ -197,6 +236,7 @@ static struct gpio_chip tegra_gpio_chip = {
.get = tegra_gpio_get,
.direction_output = tegra_gpio_direction_output,
.set = tegra_gpio_set,
+ .set_debounce = tegra_gpio_set_debounce,
.to_irq = tegra_gpio_to_irq,
.base = 0,
};
@@ -360,6 +400,14 @@ static int tegra_gpio_resume(struct device *dev)
unsigned int gpio = (b<<5) | (p<<3);
tegra_gpio_writel(tgi, bank->cnf[p],
GPIO_CNF(tgi, gpio));
+
+ if (tgi->soc->debounce_supported) {
+ tegra_gpio_writel(tgi, bank->dbc_cnt[p],
+ GPIO_DBC_CNT(tgi, gpio));
+ tegra_gpio_writel(tgi, bank->dbc_enb[p],
+ GPIO_MSK_DBC_EN(tgi, gpio));
+ }
+
tegra_gpio_writel(tgi, bank->out[p],
GPIO_OUT(tgi, gpio));
tegra_gpio_writel(tgi, bank->oe[p],
@@ -395,6 +443,13 @@ static int tegra_gpio_suspend(struct device *dev)
GPIO_OUT(tgi, gpio));
bank->oe[p] = tegra_gpio_readl(tgi,
GPIO_OE(tgi, gpio));
+ if (tgi->soc->debounce_supported) {
+ bank->dbc_enb[p] = tegra_gpio_readl(tgi,
+ GPIO_MSK_DBC_EN(tgi, gpio));
+ bank->dbc_enb[p] = (bank->dbc_enb[p] << 8) |
+ bank->dbc_enb[p];
+ }
+
bank->int_enb[p] = tegra_gpio_readl(tgi,
GPIO_INT_ENB(tgi, gpio));
bank->int_lvl[p] = tegra_gpio_readl(tgi,
@@ -547,6 +602,9 @@ static int tegra_gpio_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, tgi);

+ if (!config->debounce_supported)
+ tgi->gc->set_debounce = NULL;
+
tgi->bank_info = devm_kzalloc(&pdev->dev, tgi->bank_count *
sizeof(*tgi->bank_info), GFP_KERNEL);
if (!tgi->bank_info)
@@ -607,8 +665,10 @@ static int tegra_gpio_probe(struct platform_device *pdev)
irq_set_chained_handler_and_data(bank->irq,
tegra_gpio_irq_handler, bank);

- for (j = 0; j < 4; j++)
+ for (j = 0; j < 4; j++) {
spin_lock_init(&bank->lvl_lock[j]);
+ spin_lock_init(&bank->dbc_lock[j]);
+ }
}

tegra_gpio_debuginit(tgi);
@@ -626,7 +686,14 @@ static const struct tegra_gpio_soc_config tegra30_gpio_config = {
.upper_offset = 0x80,
};

+static const struct tegra_gpio_soc_config tegra210_gpio_config = {
+ .debounce_supported = true,
+ .bank_stride = 0x100,
+ .upper_offset = 0x80,
+};
+
static const struct of_device_id tegra_gpio_of_match[] = {
+ { .compatible = "nvidia,tegra210-gpio", .data = &tegra210_gpio_config },
{ .compatible = "nvidia,tegra30-gpio", .data = &tegra30_gpio_config },
{ .compatible = "nvidia,tegra20-gpio", .data = &tegra20_gpio_config },
{ },
--
2.1.4