linux-kernel - [PATCH v3 3/7] gpiolib: Add support for GPIO line table lookup

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Date:   Wed, 27 Nov 2019 09:42:49 +0100
From:   Geert Uytterhoeven <geert+renesas@...der.be>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Jonathan Corbet <corbet@....net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Harish Jenny K N <harish_kandiga@...tor.com>,
        Eugeniu Rosca <erosca@...adit-jv.com>
Cc:     Alexander Graf <graf@...zon.com>,
        Peter Maydell <peter.maydell@...aro.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Phil Reid <preid@...ctromag.com.au>,
        Marc Zyngier <marc.zyngier@....com>,
        Christoffer Dall <christoffer.dall@....com>,
        Magnus Damm <magnus.damm@...il.com>,
        linux-gpio@...r.kernel.org, linux-doc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
        linux-kernel@...r.kernel.org, qemu-devel@...gnu.org,
        Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH v3 3/7] gpiolib: Add support for GPIO line table lookup

Currently GPIOs can only be referred to by GPIO controller and offset in
GPIO lookup tables.

Add support for looking them up by line name.

Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
---
If this is rejected, the GPIO Aggregator documentation and code must be
updated.

v3:
  - New.
---
 drivers/gpio/gpiolib.c       | 12 ++++++++++++
 include/linux/gpio/machine.h |  2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d24a3d79dcfe69ad..cb608512ad6bbded 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4475,6 +4475,18 @@ static struct gpio_desc *gpiod_find(struct device *dev, const char *con_id,
 		if (p->con_id && (!con_id || strcmp(p->con_id, con_id)))
 			continue;
 
+		if (p->chip_hwnum == (u16)-1) {
+			desc = gpio_name_to_desc(p->chip_label);
+			if (desc) {
+				*flags = p->flags;
+				return desc;
+			}
+
+			dev_warn(dev, "cannot find GPIO line %s, deferring\n",
+				 p->chip_label);
+			return ERR_PTR(-EPROBE_DEFER);
+		}
+
 		chip = find_chip_by_name(p->chip_label);
 
 		if (!chip) {
diff --git a/include/linux/gpio/machine.h b/include/linux/gpio/machine.h
index 1ebe5be05d5f81fa..84c1c097e55eefaf 100644
--- a/include/linux/gpio/machine.h
+++ b/include/linux/gpio/machine.h
@@ -31,7 +31,7 @@ enum gpio_lookup_flags {
  */
 struct gpiod_lookup {
 	const char *chip_label;
-	u16 chip_hwnum;
+	u16 chip_hwnum;			/* if -1, chip_label is named line */
 	const char *con_id;
 	unsigned int idx;
 	unsigned long flags;
-- 
2.17.1