From: Charles Keepax <ckeepax@opensource.cirrus.com>
To: <broonie@kernel.org>, <linus.walleij@linaro.org>, <brgl@bgdev.pl>
Cc: <linux-gpio@vger.kernel.org>, <linux-spi@vger.kernel.org>,
<patches@opensource.cirrus.com>
Subject: [PATCH 1/3] gpio: swnode: Add ability to specify native chip selects for SPI
Date: Tue, 26 Mar 2024 14:11:06 +0000 [thread overview]
Message-ID: <20240326141108.1079993-2-ckeepax@opensource.cirrus.com> (raw)
In-Reply-To: <20240326141108.1079993-1-ckeepax@opensource.cirrus.com>
SPI devices can specify a cs-gpios property to enumerate their
chip selects. Under device tree, a zero entry in this property can
be used to specify that a particular chip select is using the SPI
controllers native chip select, for example:
cs-gpios = <&gpio1 0 0>, <0>;
Here the second chip select is native. However, when using swnodes
there is currently no way to specify a native chip select. The
proposal here is to register a swnode_gpio_undefined software node,
that can be specified to allow the indication of a native chip
select. For example:
static const struct software_node_ref_args device_cs_refs[] = {
{
.node = &device_gpiochip_swnode,
.nargs = 2,
.args = { 0, GPIO_ACTIVE_LOW },
},
{
.node = &swnode_gpio_undefined,
.nargs = 0,
},
};
Register the swnode as the gpiolib is initialised and
check in swnode_get_gpio_device if the returned node matches
swnode_gpio_undefined and return -ENOENT, which matches the behaviour
of the device tree system when it encounters a 0 phandle.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
---
drivers/gpio/gpiolib-swnode.c | 8 ++++++++
drivers/gpio/gpiolib.c | 9 +++++++++
include/linux/gpio/consumer.h | 4 ++++
3 files changed, 21 insertions(+)
diff --git a/drivers/gpio/gpiolib-swnode.c b/drivers/gpio/gpiolib-swnode.c
index fa52bdb1a29a..801b5a660307 100644
--- a/drivers/gpio/gpiolib-swnode.c
+++ b/drivers/gpio/gpiolib-swnode.c
@@ -17,6 +17,11 @@
#include "gpiolib.h"
#include "gpiolib-swnode.h"
+const struct software_node swnode_gpio_undefined = {
+ .name = "gpio-internal-undefined",
+};
+EXPORT_SYMBOL_GPL(swnode_gpio_undefined);
+
static void swnode_format_propname(const char *con_id, char *propname,
size_t max_size)
{
@@ -40,6 +45,9 @@ static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
if (!gdev_node || !gdev_node->name)
return ERR_PTR(-EINVAL);
+ if (!strcmp(gdev_node->name, "gpio-internal-undefined"))
+ return ERR_PTR(-ENOENT);
+
gdev = gpio_device_find_by_label(gdev_node->name);
return gdev ?: ERR_PTR(-EPROBE_DEFER);
}
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index ce94e37bcbee..e3a7e2a3a323 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -4892,8 +4892,17 @@ DEFINE_SEQ_ATTRIBUTE(gpiolib);
static int __init gpiolib_debugfs_init(void)
{
+ int ret;
+
+ ret = software_node_register(&swnode_gpio_undefined);
+ if (ret < 0) {
+ pr_err("gpiolib: failed to register swnode: %d\n", ret);
+ return ret;
+ }
+
/* /sys/kernel/debug/gpio */
debugfs_create_file("gpio", 0444, NULL, NULL, &gpiolib_fops);
+
return 0;
}
subsys_initcall(gpiolib_debugfs_init);
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index db2dfbae8edb..e685fac43398 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -12,6 +12,8 @@ struct fwnode_handle;
struct gpio_array;
struct gpio_desc;
+struct software_node;
+
/**
* struct gpio_descs - Struct containing an array of descriptors that can be
* obtained using gpiod_get_array()
@@ -54,6 +56,8 @@ enum gpiod_flags {
GPIOD_OUT_HIGH_OPEN_DRAIN = GPIOD_OUT_HIGH | GPIOD_FLAGS_BIT_OPEN_DRAIN,
};
+extern const struct software_node swnode_gpio_undefined;
+
#ifdef CONFIG_GPIOLIB
/* Return the number of GPIOs associated with a device / function */
--
2.39.2
next prev parent reply other threads:[~2024-03-26 14:11 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-26 14:11 [PATCH 0/3] Add bridged amplifiers to cs42l43 Charles Keepax
2024-03-26 14:11 ` Charles Keepax [this message]
2024-04-04 8:16 ` [PATCH 1/3] gpio: swnode: Add ability to specify native chip selects for SPI Linus Walleij
2024-04-08 13:21 ` Charles Keepax
2024-04-09 7:12 ` Linus Walleij
2024-04-09 8:44 ` Charles Keepax
2024-03-26 14:11 ` [PATCH 2/3] spi: Add a mechanism to use the fwnode name for the SPI device Charles Keepax
2024-03-26 14:11 ` [PATCH 3/3] spi: cs42l43: Add bridged cs35l56 amplifiers Charles Keepax
2024-03-27 18:34 ` kernel test robot
2024-03-28 13:15 ` kernel test robot
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