linux-kernel - [PATCH V2] gpio: brcmstb: support gpio-line-names property

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Date:   Mon,  9 Mar 2020 12:02:01 -0700
From:   Doug Berger <opendmb@...il.com>
To:     Gregory Fong <gregory.0xf0@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        bcm-kernel-feedback-list@...adcom.com, linux-gpio@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Doug Berger <opendmb@...il.com>
Subject: [PATCH V2] gpio: brcmstb: support gpio-line-names property

The default handling of the gpio-line-names property by the
gpiolib-of implementation does not work with the multiple
gpiochip banks per device structure used by the gpio-brcmstb
driver.

This commit adds driver level support for the device tree
property so that GPIO lines can be assigned friendly names.

Signed-off-by: Doug Berger <opendmb@...il.com>
---
 drivers/gpio/gpio-brcmstb.c | 44 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 44 insertions(+)

diff --git a/drivers/gpio/gpio-brcmstb.c b/drivers/gpio/gpio-brcmstb.c
index 05e3f99ae59c..fcfc1a1f1a5c 100644
--- a/drivers/gpio/gpio-brcmstb.c
+++ b/drivers/gpio/gpio-brcmstb.c
@@ -603,6 +603,49 @@ static const struct dev_pm_ops brcmstb_gpio_pm_ops = {
 	.resume_noirq = brcmstb_gpio_resume,
 };
 
+static void brcmstb_gpio_set_names(struct device *dev,
+				   struct brcmstb_gpio_bank *bank)
+{
+	struct device_node *np = dev->of_node;
+	const char **names;
+	int nstrings, base;
+	unsigned int i;
+
+	base = bank->id * MAX_GPIO_PER_BANK;
+
+	nstrings = of_property_count_strings(np, "gpio-line-names");
+	if (nstrings <= base)
+		/* Line names not present */
+		return;
+
+	names = devm_kcalloc(dev, MAX_GPIO_PER_BANK, sizeof(*names),
+			     GFP_KERNEL);
+	if (!names)
+		return;
+
+	/*
+	 * Make sure to not index beyond the end of the number of descriptors
+	 * of the GPIO device.
+	 */
+	for (i = 0; i < bank->width; i++) {
+		const char *name;
+		int ret;
+
+		ret = of_property_read_string_index(np, "gpio-line-names",
+						    base + i, &name);
+		if (ret) {
+			if (ret != -ENODATA)
+				dev_err(dev, "unable to name line %d: %d\n",
+					base + i, ret);
+			break;
+		}
+		if (*name)
+			names[i] = name;
+	}
+
+	bank->gc.names = names;
+}
+
 static int brcmstb_gpio_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -726,6 +769,7 @@ static int brcmstb_gpio_probe(struct platform_device *pdev)
 		need_wakeup_event |= !!__brcmstb_gpio_get_active_irqs(bank);
 		gc->write_reg(reg_base + GIO_MASK(bank->id), 0);
 
+		brcmstb_gpio_set_names(dev, bank);
 		err = gpiochip_add_data(gc, bank);
 		if (err) {
 			dev_err(dev, "Could not add gpiochip for bank %d\n",
-- 
2.7.4