diff --git a/drivers/gpio/gpio-ftgpio010.c b/drivers/gpio/gpio-ftgpio010.c index f548bc92e1d1..95f578804b0e 100644 --- a/drivers/gpio/gpio-ftgpio010.c +++ b/drivers/gpio/gpio-ftgpio010.c @@ -161,6 +161,73 @@ static void ftgpio_gpio_irq_handler(struct irq_desc *desc) chained_irq_exit(irqchip, desc); } +static int ftgpio_gpio_set_config(struct gpio_chip *gc, unsigned int offset, + unsigned long config) +{ + enum pin_config_param param = pinconf_to_config_param(config); + u32 arg = pinconf_to_config_argument(config); + struct ftgpio_gpio *g = gpiochip_get_data(gc); + unsigned long pclk_freq; + u32 deb_div; + u32 val; + + if (param != PIN_CONFIG_INPUT_DEBOUNCE) + return -ENOTSUPP; + + /* + * Debounce only works if interrupts are enabled. The manual + * states that if PCLK is 66 MHz, and this is set to 0x7D0, then + * PCLK is divided down to 33 kHz for the debounce timer. 0x7D0 is + * 2000 decimal, so what they mean is simply that the PCLK is + * divided by this value. + * + * As we get a debounce setting in microseconds, we calculate the + * desired period time and see if we can get a suitable debounce + * time. + */ + pclk_freq = clk_get_rate(g->clk); + deb_div = DIV_ROUND_CLOSEST(pclk_freq, arg); + + /* This register is only 24 bits wide */ + if (deb_div > (1 << 24)) + return -ENOTSUPP; + + dev_dbg(g->dev, "prescale divisor: %08x, resulting frequency %lu Hz\n", + deb_div, (pclk_freq/deb_div)); + + val = readl(g->base + GPIO_DEBOUNCE_PRESCALE); + if (val == deb_div) { + /* + * The debounce timer happens to already be set to the + * desireable value, what a coincidence! We can just enable + * debounce on this GPIO line and return. This happens more + * often than you think, for example when all GPIO keys + * on a system are requesting the same debounce interval. + */ + val = readl(g->base + GPIO_DEBOUNCE_EN); + val |= BIT(offset); + writel(val, g->base + GPIO_DEBOUNCE_EN); + return 0; + } + + val = readl(g->base + GPIO_DEBOUNCE_EN); + if (val) { + /* + * Oh no! Someone is already using the debounce with + * another setting than what we need. Bummer. + */ + return -ENOTSUPP; + } + + /* First come, first serve */ + writel(deb_div, g->base + GPIO_DEBOUNCE_PRESCALE); + /* Enable debounce */ + val |= BIT(offset); + writel(val, g->base + GPIO_DEBOUNCE_EN); + + return 0; +} + static int ftgpio_gpio_probe(struct platform_device *pdev) { struct device *dev = &pdev->dev; @@ -214,6 +281,10 @@ static int ftgpio_gpio_probe(struct platform_device *pdev) g->gc.owner = THIS_MODULE; /* ngpio is set by bgpio_init() */ + /* We need a silicon clock to do debounce */ + if (!IS_ERR(g->clk)) + g->gc.set_config = ftgpio_gpio_set_config; + ret = devm_gpiochip_add_data(dev, &g->gc, g); if (ret) goto dis_clk; @@ -223,6 +294,9 @@ static int ftgpio_gpio_probe(struct platform_device *pdev) writel(0x0, g->base + GPIO_INT_MASK); writel(~0x0, g->base + GPIO_INT_CLR); + /* Clear any use of debounce */ + writel(0x0, g->base + GPIO_DEBOUNCE_EN); + ret = gpiochip_irqchip_add(&g->gc, &ftgpio_gpio_irqchip, 0, handle_bad_irq, IRQ_TYPE_NONE);