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Subject[PATCH v3 05/18] gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL
Date
Add support for requesting lines using the GPIO_V2_GET_LINE_IOCTL, and
returning their current values using GPIO_V2_LINE_GET_VALUES_IOCTL.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
---

The struct line implementation is based on the v1 struct linehandle
implementation.

The line_ioctl() is a simple wrapper around line_get_values() here, but
will be extended with other ioctls in subsequent patches.

drivers/gpio/gpiolib-cdev.c | 413 ++++++++++++++++++++++++++++++++++++
1 file changed, 413 insertions(+)

diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
index e6c9b78adfc2..4b657492d836 100644
--- a/drivers/gpio/gpiolib-cdev.c
+++ b/drivers/gpio/gpiolib-cdev.c
@@ -1,7 +1,9 @@
// SPDX-License-Identifier: GPL-2.0

#include <linux/anon_inodes.h>
+#include <linux/atomic.h>
#include <linux/bitmap.h>
+#include <linux/build_bug.h>
#include <linux/cdev.h>
#include <linux/compat.h>
#include <linux/device.h>
@@ -34,6 +36,7 @@
* GPIO line handle management
*/

+#ifdef CONFIG_GPIO_CDEV_V1
/**
* struct linehandle_state - contains the state of a userspace handle
* @gdev: the GPIO device the handle pertains to
@@ -376,6 +379,390 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
linehandle_free(lh);
return ret;
}
+#endif /* CONFIG_GPIO_CDEV_V1 */
+
+/**
+ * struct line - contains the state of a userspace line request
+ * @gdev: the GPIO device the line request pertains to
+ * @label: consumer label used to tag descriptors
+ * @num_descs: the number of descriptors held in the descs array
+ * @descs: the GPIO descriptors held by this line request, with @num_descs
+ * elements.
+ */
+struct line {
+ struct gpio_device *gdev;
+ const char *label;
+ u32 num_descs;
+ struct gpio_desc *descs[];
+};
+
+#define GPIO_V2_LINE_BIAS_FLAGS \
+ (GPIO_V2_LINE_FLAG_BIAS_PULL_UP | \
+ GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN | \
+ GPIO_V2_LINE_FLAG_BIAS_DISABLED)
+
+#define GPIO_V2_LINE_DIRECTION_FLAGS \
+ (GPIO_V2_LINE_FLAG_INPUT | \
+ GPIO_V2_LINE_FLAG_OUTPUT)
+
+#define GPIO_V2_LINE_DRIVE_FLAGS \
+ (GPIO_V2_LINE_FLAG_OPEN_DRAIN | \
+ GPIO_V2_LINE_FLAG_OPEN_SOURCE)
+
+#define GPIO_V2_LINE_VALID_FLAGS \
+ (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \
+ GPIO_V2_LINE_DIRECTION_FLAGS | \
+ GPIO_V2_LINE_DRIVE_FLAGS | \
+ GPIO_V2_LINE_BIAS_FLAGS)
+
+static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc,
+ int line_idx)
+{
+ int i;
+ u64 mask = BIT_ULL(line_idx);
+
+ for (i = 0; i < lc->num_attrs; i++) {
+ if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_FLAGS) &&
+ (lc->attrs[i].mask & mask))
+ return lc->attrs[i].attr.flags;
+ }
+ return lc->flags;
+}
+
+static int gpio_v2_line_config_output_value(struct gpio_v2_line_config *lc,
+ int line_idx)
+{
+ int i;
+ u64 mask = BIT_ULL(line_idx);
+
+ for (i = 0; i < lc->num_attrs; i++) {
+ if ((lc->attrs[i].attr.id == GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES) &&
+ (lc->attrs[i].mask & mask))
+ return !!(lc->attrs[i].attr.values & mask);
+ }
+ return 0;
+}
+
+static int gpio_v2_line_flags_validate(u64 flags)
+{
+ /* Return an error if an unknown flag is set */
+ if (flags & ~GPIO_V2_LINE_VALID_FLAGS)
+ return -EINVAL;
+
+ /*
+ * Do not allow both INPUT & OUTPUT flags to be set as they are
+ * contradictory.
+ */
+ if ((flags & GPIO_V2_LINE_FLAG_INPUT) &&
+ (flags & GPIO_V2_LINE_FLAG_OUTPUT))
+ return -EINVAL;
+
+ /*
+ * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
+ * the hardware actually supports enabling both at the same time the
+ * electrical result would be disastrous.
+ */
+ if ((flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN) &&
+ (flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE))
+ return -EINVAL;
+
+ /* Drive requires explicit output direction. */
+ if ((flags & GPIO_V2_LINE_DRIVE_FLAGS) &&
+ !(flags & GPIO_V2_LINE_FLAG_OUTPUT))
+ return -EINVAL;
+
+ /* Bias requies explicit direction. */
+ if ((flags & GPIO_V2_LINE_BIAS_FLAGS) &&
+ !(flags & GPIO_V2_LINE_DIRECTION_FLAGS))
+ return -EINVAL;
+
+ /* Only one bias flag can be set. */
+ if (((flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED) &&
+ (flags & (GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN |
+ GPIO_V2_LINE_FLAG_BIAS_PULL_UP))) ||
+ ((flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN) &&
+ (flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)))
+ return -EINVAL;
+
+ return 0;
+}
+
+static int gpio_v2_line_config_validate(struct gpio_v2_line_config *lc,
+ int num_lines)
+{
+ int i, ret;
+ u64 flags;
+
+ if (lc->num_attrs > GPIO_V2_LINE_NUM_ATTRS_MAX)
+ return -EINVAL;
+
+ if (memchr_inv(lc->padding, 0, sizeof(lc->padding)))
+ return -EINVAL;
+
+ for (i = 0; i < num_lines; i++) {
+ flags = gpio_v2_line_config_flags(lc, i);
+ ret = gpio_v2_line_flags_validate(flags);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
+static void gpio_v2_line_config_flags_to_desc_flags(u64 flags,
+ unsigned long *flagsp)
+{
+ assign_bit(FLAG_ACTIVE_LOW, flagsp,
+ flags & GPIO_V2_LINE_FLAG_ACTIVE_LOW);
+ if (flags & GPIO_V2_LINE_FLAG_OUTPUT)
+ set_bit(FLAG_IS_OUT, flagsp);
+ else if (flags & GPIO_V2_LINE_FLAG_INPUT)
+ clear_bit(FLAG_IS_OUT, flagsp);
+ assign_bit(FLAG_OPEN_DRAIN, flagsp,
+ flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN);
+ assign_bit(FLAG_OPEN_SOURCE, flagsp,
+ flags & GPIO_V2_LINE_FLAG_OPEN_SOURCE);
+ assign_bit(FLAG_PULL_UP, flagsp,
+ flags & GPIO_V2_LINE_FLAG_BIAS_PULL_UP);
+ assign_bit(FLAG_PULL_DOWN, flagsp,
+ flags & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN);
+ assign_bit(FLAG_BIAS_DISABLE, flagsp,
+ flags & GPIO_V2_LINE_FLAG_BIAS_DISABLED);
+}
+
+static long line_get_values(struct line *line, void __user *ip)
+{
+ struct gpio_v2_line_values lv;
+ DECLARE_BITMAP(vals, GPIO_V2_LINES_MAX);
+ DECLARE_BITMAP(mask, GPIO_V2_LINES_MAX);
+ struct gpio_desc **descs;
+ int ret, i, didx, num_get = 0;
+
+ /* NOTE: It's ok to read values of output lines. */
+ if (copy_from_user(&lv, ip, sizeof(lv)))
+ return -EFAULT;
+
+ if (lv.mask == 0)
+ return -EINVAL;
+
+ bitmap_from_u64(mask, lv.mask);
+ num_get = bitmap_weight(mask, line->num_descs);
+ if (num_get == line->num_descs) {
+ descs = line->descs;
+ } else {
+ descs = kmalloc_array(num_get, sizeof(*descs), GFP_KERNEL);
+ for (didx = 0, i = 0; i < line->num_descs; i++) {
+ if (test_bit(i, mask)) {
+ descs[didx] = line->descs[i];
+ didx++;
+ }
+ }
+ }
+ ret = gpiod_get_array_value_complex(false,
+ true,
+ num_get,
+ descs,
+ NULL,
+ vals);
+
+ if (descs != line->descs)
+ kfree(descs);
+ if (ret)
+ return ret;
+
+ lv.bits = 0;
+ for (didx = 0, i = 0; i < line->num_descs; i++) {
+ if (test_bit(i, mask)) {
+ if (test_bit(didx, vals))
+ lv.bits |= BIT_ULL(i);
+ didx++;
+ }
+ }
+
+ if (copy_to_user(ip, &lv, sizeof(lv)))
+ return -EFAULT;
+
+ return 0;
+}
+
+static long line_ioctl(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ struct line *line = file->private_data;
+ void __user *ip = (void __user *)arg;
+
+ if (cmd == GPIO_V2_LINE_GET_VALUES_IOCTL)
+ return line_get_values(line, ip);
+
+ return -EINVAL;
+}
+
+#ifdef CONFIG_COMPAT
+static long line_ioctl_compat(struct file *file, unsigned int cmd,
+ unsigned long arg)
+{
+ return line_ioctl(file, cmd, (unsigned long)compat_ptr(arg));
+}
+#endif
+
+static void line_free(struct line *line)
+{
+ int i;
+
+ for (i = 0; i < line->num_descs; i++) {
+ if (line->descs[i])
+ gpiod_free(line->descs[i]);
+ }
+ kfree(line->label);
+ put_device(&line->gdev->dev);
+ kfree(line);
+}
+
+static int line_release(struct inode *inode, struct file *file)
+{
+ struct line *line = file->private_data;
+
+ line_free(line);
+ return 0;
+}
+
+static const struct file_operations line_fileops = {
+ .release = line_release,
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .unlocked_ioctl = line_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = line_ioctl_compat,
+#endif
+};
+
+static int line_create(struct gpio_device *gdev, void __user *ip)
+{
+ struct gpio_v2_line_request lr;
+ struct line *line;
+ struct file *file;
+ int fd, i, ret;
+ struct gpio_v2_line_config *lc;
+ unsigned long flags;
+
+ if (copy_from_user(&lr, ip, sizeof(lr)))
+ return -EFAULT;
+ if ((lr.num_lines == 0) || (lr.num_lines > GPIO_V2_LINES_MAX))
+ return -EINVAL;
+
+ if (memchr_inv(lr.padding, 0, sizeof(lr.padding)))
+ return -EINVAL;
+
+ lc = &lr.config;
+ ret = gpio_v2_line_config_validate(lc, lr.num_lines);
+ if (ret)
+ return ret;
+
+ line = kzalloc(struct_size(line, descs, lr.num_lines),
+ GFP_KERNEL);
+ if (!line)
+ return -ENOMEM;
+
+ line->gdev = gdev;
+ get_device(&gdev->dev);
+
+ /* Make sure this is terminated */
+ lr.consumer[sizeof(lr.consumer)-1] = '\0';
+ if (strlen(lr.consumer)) {
+ line->label = kstrdup(lr.consumer, GFP_KERNEL);
+ if (!line->label) {
+ ret = -ENOMEM;
+ goto out_free_line;
+ }
+ }
+
+ line->num_descs = lr.num_lines;
+
+ /* Request each GPIO */
+ for (i = 0; i < lr.num_lines; i++) {
+ u32 offset = lr.offsets[i];
+ struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset);
+
+ if (IS_ERR(desc)) {
+ ret = PTR_ERR(desc);
+ goto out_free_line;
+ }
+
+ ret = gpiod_request(desc, line->label);
+ if (ret)
+ goto out_free_line;
+
+ line->descs[i] = desc;
+ flags = gpio_v2_line_config_flags(lc, i);
+ gpio_v2_line_config_flags_to_desc_flags(flags, &desc->flags);
+
+ ret = gpiod_set_transitory(desc, false);
+ if (ret < 0)
+ goto out_free_line;
+
+ /*
+ * Lines have to be requested explicitly for input
+ * or output, else the line will be treated "as is".
+ */
+ if (flags & GPIO_V2_LINE_FLAG_OUTPUT) {
+ int val = gpio_v2_line_config_output_value(lc, i);
+
+ ret = gpiod_direction_output(desc, val);
+ if (ret)
+ goto out_free_line;
+ } else if (flags & GPIO_V2_LINE_FLAG_INPUT) {
+ ret = gpiod_direction_input(desc);
+ if (ret)
+ goto out_free_line;
+ }
+
+ blocking_notifier_call_chain(&desc->gdev->notifier,
+ GPIOLINE_CHANGED_REQUESTED, desc);
+
+ dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
+ offset);
+ }
+
+ fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC);
+ if (fd < 0) {
+ ret = fd;
+ goto out_free_line;
+ }
+
+ file = anon_inode_getfile("gpio-line",
+ &line_fileops,
+ line,
+ O_RDONLY | O_CLOEXEC);
+ if (IS_ERR(file)) {
+ ret = PTR_ERR(file);
+ goto out_put_unused_fd;
+ }
+
+ lr.fd = fd;
+ if (copy_to_user(ip, &lr, sizeof(lr))) {
+ /*
+ * fput() will trigger the release() callback, so do not go onto
+ * the regular error cleanup path here.
+ */
+ fput(file);
+ put_unused_fd(fd);
+ return -EFAULT;
+ }
+
+ fd_install(fd, file);
+
+ dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
+ line->num_descs);
+
+ return 0;
+
+out_put_unused_fd:
+ put_unused_fd(fd);
+out_free_line:
+ line_free(line);
+ return ret;
+}
+
+#ifdef CONFIG_GPIO_CDEV_V1

/*
* GPIO line event management
@@ -745,6 +1132,8 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
return ret;
}

+#endif /* CONFIG_GPIO_CDEV_V1 */
+
static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
struct gpioline_info *info)
{
@@ -850,6 +1239,7 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (copy_to_user(ip, &chipinfo, sizeof(chipinfo)))
return -EFAULT;
return 0;
+#ifdef CONFIG_GPIO_CDEV_V1
} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
struct gpioline_info lineinfo;

@@ -892,6 +1282,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
}

return 0;
+#endif /* CONFIG_GPIO_CDEV_V1 */
+ } else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
+ return line_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
if (copy_from_user(&offset, ip, sizeof(offset)))
return -EFAULT;
@@ -1118,4 +1511,24 @@ int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt)
void gpiolib_cdev_unregister(struct gpio_device *gdev)
{
cdev_device_del(&gdev->chrdev, &gdev->dev);
+
+ /*
+ * array sizes must ensure 64-bit alignment and not create holes in
+ * the struct packing.
+ */
+ BUILD_BUG_ON(GPIO_V2_LINES_MAX % 2);
+ BUILD_BUG_ON(GPIO_MAX_NAME_SIZE % 8);
+
+ /*
+ * check that uAPI structs are 64-bit aligned for 32/64-bit
+ * compatibility
+ */
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_attribute) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_config_attribute) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_config) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_request) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_info) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_info_changed) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_event) % 8);
+ BUILD_BUG_ON(sizeof(struct gpio_v2_line_values) % 8);
}
--
2.28.0
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