Message-Id: <20230901183240.102701-1-brgl@bgdev.pl>
Date:   Fri,  1 Sep 2023 20:32:40 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Kent Gibson <warthog618@...il.com>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH] gpio: sim: don't fiddle with GPIOLIB private members

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

We access internals of struct gpio_device and struct gpio_desc because
it's easier but it can actually be avoided and we're working towards a
better encapsulation of GPIO data structures across the kernel so let's
start at home.

Instead of checking gpio_desc flags, let's just track the requests of
GPIOs in the driver. We also already store the information about
direction of simulated lines.

For kobjects needed by sysfs callbacks: we can leverage the fact that
once created for a software node, struct device is accessible from that
fwnode_handle. We don't need to dereference gpio_device.

While at it: fix one line break and remove the untrue part about
configfs callbacks using dev_get_drvdata() from a comment.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
 drivers/gpio/gpio-sim.c | 49 +++++++++++++++++++++++++++--------------
 1 file changed, 32 insertions(+), 17 deletions(-)

diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
index 271db3639a78..5f52d77567a1 100644
--- a/drivers/gpio/gpio-sim.c
+++ b/drivers/gpio/gpio-sim.c
@@ -12,6 +12,7 @@
 #include <linux/completion.h>
 #include <linux/configfs.h>
 #include <linux/device.h>
+#include <linux/gpio/consumer.h>
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
 #include <linux/idr.h>
@@ -30,8 +31,6 @@
 #include <linux/string_helpers.h>
 #include <linux/sysfs.h>
 
-#include "gpiolib.h"
-
 #define GPIO_SIM_NGPIO_MAX	1024
 #define GPIO_SIM_PROP_MAX	4 /* Max 3 properties + sentinel. */
 #define GPIO_SIM_NUM_ATTRS	3 /* value, pull and sentinel */
@@ -40,6 +39,8 @@ static DEFINE_IDA(gpio_sim_ida);
 
 struct gpio_sim_chip {
 	struct gpio_chip gc;
+	struct fwnode_handle *swnode;
+	unsigned long *request_map;
 	unsigned long *direction_map;
 	unsigned long *value_map;
 	unsigned long *pull_map;
@@ -63,16 +64,11 @@ static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
 			       unsigned int offset, int value)
 {
 	int irq, irq_type, ret;
-	struct gpio_desc *desc;
-	struct gpio_chip *gc;
-
-	gc = &chip->gc;
-	desc = &gc->gpiodev->descs[offset];
 
 	guard(mutex)(&chip->lock);
 
-	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
-	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
+	if (test_bit(offset, chip->request_map) &&
+	    test_bit(offset, chip->direction_map)) {
 		if (value == !!test_bit(offset, chip->value_map))
 			goto set_pull;
 
@@ -99,8 +95,8 @@ static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
 
 set_value:
 	/* Change the value unless we're actively driving the line. */
-	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
-	    !test_bit(FLAG_IS_OUT, &desc->flags))
+	if (!test_bit(offset, chip->request_map) ||
+	    test_bit(offset, chip->direction_map))
 		__assign_bit(offset, chip->value_map, value);
 
 set_pull:
@@ -181,7 +177,7 @@ static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)
 }
 
 static int gpio_sim_set_config(struct gpio_chip *gc,
-				  unsigned int offset, unsigned long config)
+			       unsigned int offset, unsigned long config)
 {
 	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
 
@@ -204,13 +200,25 @@ static int gpio_sim_to_irq(struct gpio_chip *gc, unsigned int offset)
 	return irq_create_mapping(chip->irq_sim, offset);
 }
 
-static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
+static int gpio_sim_request(struct gpio_chip *gc, unsigned int offset)
 {
 	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
 
 	scoped_guard(mutex, &chip->lock)
+		__set_bit(offset, chip->request_map);
+
+	return 0;
+}
+
+static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	scoped_guard(mutex, &chip->lock) {
 		__assign_bit(offset, chip->value_map,
 			     !!test_bit(offset, chip->pull_map));
+		__clear_bit(offset, chip->request_map);
+	}
 }
 
 static ssize_t gpio_sim_sysfs_val_show(struct device *dev,
@@ -295,7 +303,7 @@ static void gpio_sim_sysfs_remove(void *data)
 {
 	struct gpio_sim_chip *chip = data;
 
-	sysfs_remove_groups(&chip->gc.gpiodev->dev.kobj, chip->attr_groups);
+	sysfs_remove_groups(&chip->swnode->dev->kobj, chip->attr_groups);
 }
 
 static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
@@ -352,7 +360,7 @@ static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
 		chip->attr_groups[i] = attr_group;
 	}
 
-	ret = sysfs_create_groups(&chip->gc.gpiodev->dev.kobj,
+	ret = sysfs_create_groups(&chip->swnode->dev->kobj,
 				  chip->attr_groups);
 	if (ret)
 		return ret;
@@ -387,6 +395,12 @@ static int gpio_sim_add_bank(struct fwnode_handle *swnode, struct device *dev)
 	if (!chip)
 		return -ENOMEM;
 
+	chip->swnode = swnode;
+
+	chip->request_map = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->request_map)
+		return -ENOMEM;
+
 	chip->direction_map = devm_bitmap_alloc(dev, num_lines, GFP_KERNEL);
 	if (!chip->direction_map)
 		return -ENOMEM;
@@ -432,6 +446,7 @@ static int gpio_sim_add_bank(struct fwnode_handle *swnode, struct device *dev)
 	gc->get_direction = gpio_sim_get_direction;
 	gc->set_config = gpio_sim_set_config;
 	gc->to_irq = gpio_sim_to_irq;
+	gc->request = gpio_sim_request;
 	gc->free = gpio_sim_free;
 	gc->can_sleep = true;
 
@@ -439,8 +454,8 @@ static int gpio_sim_add_bank(struct fwnode_handle *swnode, struct device *dev)
 	if (ret)
 		return ret;
 
-	/* Used by sysfs and configfs callbacks. */
-	dev_set_drvdata(&gc->gpiodev->dev, chip);
+	/* Used by sysfs callbacks. */
+	dev_set_drvdata(swnode->dev, chip);
 
 	return gpio_sim_setup_sysfs(chip);
 }
-- 
2.39.2

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