@@ -20,6 +20,7 @@
#include <linux/cdev.h>
#include <linux/fs.h>
#include <linux/uaccess.h>
+#include <linux/anon_inodes.h>
#include <uapi/linux/gpio.h>
#include "gpiolib.h"
@@ -308,6 +309,193 @@ static int gpiochip_set_desc_names(struct gpio_chip *gc)
return 0;
}
+
+/*
+ * GPIO line handle management
+ */
+
+/**
+ * struct linehandle_state - contains the state of a userspace handle
+ * @gdev: the GPIO device the handle pertains to
+ * @label: consumer label used to tag descriptors
+ * @descs: the GPIO descriptors held by this handle
+ * @numdescs: the number of descriptors held in the descs array
+ */
+struct linehandle_state {
+ struct gpio_device *gdev;
+ char *label;
+ struct gpio_desc *descs[GPIOHANDLES_MAX];
+ u32 numdescs;
+};
+
+static long linehandle_ioctl(struct file *filep, unsigned int cmd,
+ unsigned long arg)
+{
+ struct linehandle_state *lh = filep->private_data;
+ int __user *ip = (int __user *)arg;
+ struct gpiohandle_data ghd;
+ int i;
+
+ if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) {
+ int val;
+
+ /* TODO: check if descriptors are really input */
+ for (i = 0; i < lh->numdescs; i++) {
+ val = gpiod_get_value(lh->descs[i]);
+ if (val < 0)
+ return val;
+ ghd.values[i] = val;
+ }
+
+ if (copy_to_user(ip, &ghd, sizeof(ghd)))
+ return -EFAULT;
+
+ return 0;
+ } else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) {
+ int vals[GPIOHANDLES_MAX];
+
+ /* TODO: check if descriptors are really output */
+ if (copy_from_user(&ghd, ip, sizeof(ghd)))
+ return -EFAULT;
+
+ /* Clamp all values to [0,1] */
+ for (i = 0; i < lh->numdescs; i++)
+ vals[i] = !!ghd.values[i];
+
+ /* Reuse the array setting function */
+ gpiod_set_array_value_complex(false,
+ true,
+ lh->numdescs,
+ lh->descs,
+ vals);
+ return 0;
+ }
+ return -EINVAL;
+}
+
+static int linehandle_release(struct inode *inode, struct file *filep)
+{
+ struct linehandle_state *lh = filep->private_data;
+ struct gpio_device *gdev = lh->gdev;
+ int i;
+
+ for (i = 0; i < lh->numdescs; i++)
+ gpiod_free(lh->descs[i]);
+ devm_kfree(&gdev->dev, lh->label);
+ devm_kfree(&gdev->dev, lh);
+ put_device(&gdev->dev);
+ return 0;
+}
+
+static const struct file_operations linehandle_fileops = {
+ .release = linehandle_release,
+ .owner = THIS_MODULE,
+ .llseek = noop_llseek,
+ .unlocked_ioctl = linehandle_ioctl,
+ .compat_ioctl = linehandle_ioctl,
+};
+
+static int linehandle_create(struct gpio_device *gdev, int __user *ip)
+{
+ struct gpiohandle_request handlereq;
+ struct linehandle_state *lh;
+ int fd, i, ret;
+
+ if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
+ return -EFAULT;
+
+ /*
+ * Use devm_* calls with devm_*free() so we can request
+ * and free the memory for these while still be sure that
+ * they will eventually go away with the device if not
+ * before that.
+ */
+ lh = devm_kzalloc(&gdev->dev, sizeof(*lh), GFP_KERNEL);
+ if (!lh)
+ return -ENOMEM;
+ lh->gdev = gdev;
+ get_device(&gdev->dev);
+
+ fd = anon_inode_getfd("gpio-linehandle",
+ &linehandle_fileops,
+ lh,
+ O_RDONLY | O_CLOEXEC);
+ if (fd < 0) {
+ ret = fd;
+ goto out_free_lh;
+ }
+
+ /* Make sure this is terminated */
+ handlereq.consumer_label[sizeof(handlereq.consumer_label)-1] = '\0';
+ if (strlen(handlereq.consumer_label)) {
+ lh->label = devm_kstrdup(&gdev->dev,
+ handlereq.consumer_label,
+ GFP_KERNEL);
+ if (!lh->label) {
+ ret = -ENOMEM;
+ goto out_free_lh;
+ }
+ }
+
+ /* Request each GPIO */
+ for (i = 0; i < handlereq.lines; i++) {
+ u32 offset = handlereq.lineoffsets[i];
+ u32 lflags = handlereq.flags;
+ struct gpio_desc *desc;
+
+ desc = &gdev->descs[offset];
+ ret = gpiod_request(desc, lh->label);
+ if (ret)
+ goto out_free_descs;
+ lh->descs[i] = desc;
+
+ if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW)
+ set_bit(FLAG_ACTIVE_LOW, &desc->flags);
+ if (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN)
+ set_bit(FLAG_OPEN_DRAIN, &desc->flags);
+ if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)
+ set_bit(FLAG_OPEN_SOURCE, &desc->flags);
+
+ /*
+ * Lines have to be requested explicitly for input
+ * or output, else the line will be treated "as is".
+ */
+ if (lflags & GPIOHANDLE_REQUEST_OUTPUT) {
+ int val = !!handlereq.default_values[i];
+
+ ret = gpiod_direction_output(desc, val);
+ if (ret)
+ goto out_free_descs;
+ } else if (lflags & GPIOHANDLE_REQUEST_INPUT) {
+ ret = gpiod_direction_input(desc);
+ if (ret)
+ goto out_free_descs;
+ }
+ dev_dbg(&gdev->dev, "registered chardev handle for pin %d\n",
+ offset);
+ }
+ lh->numdescs = handlereq.lines;
+ dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n",
+ lh->numdescs);
+
+ handlereq.fd = fd;
+ if (copy_to_user(ip, &handlereq, sizeof(handlereq))) {
+ ret = -EFAULT;
+ goto out_free_descs;
+ }
+
+ return 0;
+
+out_free_descs:
+ for (; i >= 0; i--)
+ gpiod_free(lh->descs[i]);
+ devm_kfree(&gdev->dev, lh->label);
+out_free_lh:
+ devm_kfree(&gdev->dev, lh);
+ put_device(&gdev->dev);
+ return ret;
+}
+
/**
* gpio_ioctl() - ioctl handler for the GPIO chardev
*/
@@ -383,6 +571,8 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
return -EFAULT;
return 0;
+ } else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
+ return linehandle_create(gdev, ip);
}
return -EINVAL;
}
@@ -1,7 +1,7 @@
/*
* <linux/gpio.h> - userspace ABI for the GPIO character devices
*
- * Copyright (C) 2015 Linus Walleij
+ * Copyright (C) 2016 Linus Walleij
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 as published by
@@ -26,8 +26,8 @@ struct gpiochip_info {
__u32 lines;
};
-/* Line is in use by the kernel */
-#define GPIOLINE_FLAG_KERNEL (1UL << 0)
+/* Informational flags */
+#define GPIOLINE_FLAG_KERNEL (1UL << 0) /* Line used by the kernel */
#define GPIOLINE_FLAG_IS_OUT (1UL << 1)
#define GPIOLINE_FLAG_ACTIVE_LOW (1UL << 2)
#define GPIOLINE_FLAG_OPEN_DRAIN (1UL << 3)
@@ -52,7 +52,62 @@ struct gpioline_info {
char consumer[32];
};
+/* Maximum number of requested handles */
+#define GPIOHANDLES_MAX 64
+
+/* Request flags */
+#define GPIOHANDLE_REQUEST_INPUT (1UL << 0)
+#define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1)
+#define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2)
+#define GPIOHANDLE_REQUEST_OPEN_DRAIN (1UL << 3)
+#define GPIOHANDLE_REQUEST_OPEN_SOURCE (1UL << 4)
+
+/**
+ * struct gpiohandle_request - Information about a GPIO handle request
+ * @lineoffsets: an array desired lines, specified by offset index for the
+ * associated GPIO device
+ * @flags: desired flags for the desired GPIO lines, such as
+ * GPIOLINE_IS_OUT, GPIOLINE_FLAG_ACTIVE_LOW etc, OR:ed together.
+ * Note that even if multiple lines are requested, the same flags
+ * must be applicable to all of them, if you want lines with individual
+ * flags set, request them one by one. It is possible to select
+ * a batch of input or output lines, but they must all have the same
+ * characteristics, i.e. all inputs or all outputs, all active low etc
+ * @default_values: if the GPIOLINE_FLAG_IS_OUT is set for a requested
+ * line, this specifies the default output value, should be 0 (low) or
+ * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
+ * @consumer_label: a desired consumer label for the selected GPIO line(s)
+ * such as "my-bitbanged-relay"
+ * @lines: number of lines requested in this request, i.e. the number of
+ * valid fields in the above arrays, set to 1 to request a single line
+ * @fd: if successful this field will contain a valid anonymous file handle
+ * after a GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value
+ * means error
+ */
+struct gpiohandle_request {
+ __u32 lineoffsets[GPIOHANDLES_MAX];
+ __u32 flags;
+ __u8 default_values[GPIOHANDLES_MAX];
+ char consumer_label[32];
+ __u32 lines;
+ int fd;
+};
+
#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info)
#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
+#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
+
+/**
+ * struct gpiohandle_data - Information of values on a GPIO handle
+ * @values: when getting the state of lines this contains the current
+ * state of a line, when setting the state of lines these should contain
+ * the desired target state
+ */
+struct gpiohandle_data {
+ __u8 values[GPIOHANDLES_MAX];
+};
+
+#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOR(0xB4, 0x08, struct gpiohandle_data)
+#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOR(0xB4, 0x09, struct gpiohandle_data)
#endif /* _UAPI_GPIO_H_ */
This adds a userspace ABI for reading and writing GPIO lines. The mechanism returns an anonymous file handle to a request to read/write n offsets from a gpiochip. This file handle in turn accepts two ioctl()s: one that reads and one that writes values to the selected lines. - Handles can be requested as input/output, active low, open drain, open source, however when you issue a request for n lines with GPIO_GET_LINEHANDLE_IOCTL, they must all have the same flags, i.e. all inputs or all outputs, all open drain etc. If a granular control of the flags for each line is desired, they need to be requested individually, not in a batch. - The GPIOHANDLE_GET_LINE_VALUES_IOCTL read ioctl() can be issued also to output lines to verify that the hardware is in the expected state. - It reads and writes up to GPIOHANDLES_MAX lines at once, utilizing the .set_multiple() call in the driver if possible, making the call efficient if several lines can be written with a single register update. The limitation of GPIOHANDLES_MAX to 64 lines is done under the assumption that we may expect hardware that can issue a transaction updating 64 bits at an instant but unlikely anything larger than that. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> --- drivers/gpio/gpiolib.c | 190 ++++++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/gpio.h | 61 ++++++++++++++- 2 files changed, 248 insertions(+), 3 deletions(-) -- 2.4.11 -- To unsubscribe from this list: send the line "unsubscribe linux-gpio" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html