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Subject[PATCH 1/2] gpio: tegra186: Force one interrupt per bank
Date
From: Thierry Reding <treding@nvidia.com>

Newer chips support up to 8 interrupts per bank, which can be useful to
balance the load and decrease latency. However, it also required a very
complicated interrupt routing to be set up. To keep things simple for
now, ensure that a single interrupt per bank is enforced, even if all
possible interrupts are described in device tree.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
drivers/gpio/gpio-tegra186.c | 68 ++++++++++++++++++++++++++++++++----
1 file changed, 62 insertions(+), 6 deletions(-)

diff --git a/drivers/gpio/gpio-tegra186.c b/drivers/gpio/gpio-tegra186.c
index c99858f40a27..1bc4152e0275 100644
--- a/drivers/gpio/gpio-tegra186.c
+++ b/drivers/gpio/gpio-tegra186.c
@@ -81,6 +81,8 @@ struct tegra_gpio {
unsigned int *irq;

const struct tegra_gpio_soc *soc;
+ unsigned int num_irqs_per_bank;
+ unsigned int num_banks;

void __iomem *secure;
void __iomem *base;
@@ -594,6 +596,28 @@ static void tegra186_gpio_init_route_mapping(struct tegra_gpio *gpio)
}
}

+static unsigned int tegra186_gpio_irqs_per_bank(struct tegra_gpio *gpio)
+{
+ struct device *dev = gpio->gpio.parent;
+
+ if (gpio->num_irq > gpio->num_banks) {
+ if (gpio->num_irq % gpio->num_banks != 0)
+ goto error;
+ }
+
+ if (gpio->num_irq < gpio->num_banks)
+ goto error;
+
+ gpio->num_irqs_per_bank = gpio->num_irq / gpio->num_banks;
+
+ return 0;
+
+error:
+ dev_err(dev, "invalid number of interrupts (%u) for %u banks\n",
+ gpio->num_irq, gpio->num_banks);
+ return -EINVAL;
+}
+
static int tegra186_gpio_probe(struct platform_device *pdev)
{
unsigned int i, j, offset;
@@ -608,7 +632,17 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
return -ENOMEM;

gpio->soc = device_get_match_data(&pdev->dev);
+ gpio->gpio.label = gpio->soc->name;
+ gpio->gpio.parent = &pdev->dev;
+
+ /* count the number of banks in the controller */
+ for (i = 0; i < gpio->soc->num_ports; i++)
+ if (gpio->soc->ports[i].bank > gpio->num_banks)
+ gpio->num_banks = gpio->soc->ports[i].bank;
+
+ gpio->num_banks++;

+ /* get register apertures */
gpio->secure = devm_platform_ioremap_resource_byname(pdev, "security");
if (IS_ERR(gpio->secure)) {
gpio->secure = devm_platform_ioremap_resource(pdev, 0);
@@ -629,6 +663,10 @@ static int tegra186_gpio_probe(struct platform_device *pdev)

gpio->num_irq = err;

+ err = tegra186_gpio_irqs_per_bank(gpio);
+ if (err < 0)
+ return err;
+
gpio->irq = devm_kcalloc(&pdev->dev, gpio->num_irq, sizeof(*gpio->irq),
GFP_KERNEL);
if (!gpio->irq)
@@ -642,9 +680,6 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
gpio->irq[i] = err;
}

- gpio->gpio.label = gpio->soc->name;
- gpio->gpio.parent = &pdev->dev;
-
gpio->gpio.request = gpiochip_generic_request;
gpio->gpio.free = gpiochip_generic_free;
gpio->gpio.get_direction = tegra186_gpio_get_direction;
@@ -708,7 +743,30 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
irq->parent_handler = tegra186_gpio_irq;
irq->parent_handler_data = gpio;
irq->num_parents = gpio->num_irq;
- irq->parents = gpio->irq;
+
+ /*
+ * To simplify things, use a single interrupt per bank for now. Some
+ * chips support up to 8 interrupts per bank, which can be useful to
+ * distribute the load and decrease the processing latency for GPIOs
+ * but it also requires a more complicated interrupt routing than we
+ * currently program.
+ */
+ if (gpio->num_irqs_per_bank > 1) {
+ irq->parents = devm_kcalloc(&pdev->dev, gpio->num_banks,
+ sizeof(*irq->parents), GFP_KERNEL);
+ if (!irq->parents)
+ return -ENOMEM;
+
+ for (i = 0; i < gpio->num_banks; i++)
+ irq->parents[i] = gpio->irq[i * gpio->num_irqs_per_bank];
+
+ irq->num_parents = gpio->num_banks;
+ } else {
+ irq->num_parents = gpio->num_irq;
+ irq->parents = gpio->irq;
+ }
+
+ tegra186_gpio_init_route_mapping(gpio);

np = of_find_matching_node(NULL, tegra186_pmc_of_match);
if (np) {
@@ -719,8 +777,6 @@ static int tegra186_gpio_probe(struct platform_device *pdev)
return -EPROBE_DEFER;
}

- tegra186_gpio_init_route_mapping(gpio);
-
irq->map = devm_kcalloc(&pdev->dev, gpio->gpio.ngpio,
sizeof(*irq->map), GFP_KERNEL);
if (!irq->map)
--
2.33.0
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