[PATCH v2 2/2] pinctrl: pinmux: Add pinmux-select debugfs file

Drew Fustini
2021-02-10T07:52:56Z

Add "pinmux-select" to debugfs which will activate a function and group
when 2 integers "<function-selector> <group-selector>" are written to
the file. The write operation pinmux_select() handles this by checking
if fsel and gsel are valid selectors and then calling ops->set_mux().

The existing "pinmux-functions" debugfs file lists the pin functions
registered for the pin controller. For example:

function: pinmux-uart0, groups = [ pinmux-uart0-pins ]
function: pinmux-mmc0, groups = [ pinmux-mmc0-pins ]
function: pinmux-mmc1, groups = [ pinmux-mmc1-pins ]
function: pinmux-i2c0, groups = [ pinmux-i2c0-pins ]
function: pinmux-i2c1, groups = [ pinmux-i2c1-pins ]
function: pinmux-spi1, groups = [ pinmux-spi1-pins ]

To activate function pinmux-i2c1 (fsel 4) and group pinmux-i2c1-pins
(gsel 4):

echo '4 4' > pinmux-select

Signed-off-by: Drew Fustini <drew@beagleboard.org>
---
drivers/pinctrl/pinmux.c | 106 +++++++++++++++++++++++++++++++++++++++
1 file changed, 106 insertions(+)

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index 7f6190eaedbb..b8cd0c3bedf7 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -673,6 +673,110 @@ void pinmux_show_setting(struct seq_file *s,
DEFINE_SHOW_ATTRIBUTE(pinmux_functions);
DEFINE_SHOW_ATTRIBUTE(pinmux_pins);

+
+#define PINMUX_MAX_NAME 64
+static ssize_t pinmux_select(struct file *file, const char __user *user_buf,
+ size_t len, loff_t *ppos)
+{
+ struct seq_file *sfile = file->private_data;
+ struct pinctrl_dev *pctldev = sfile->private;
+ const struct pinmux_ops *pmxops = pctldev->desc->pmxops;
+ const char *const *groups;
+ char *buf, *fname, *gname;
+ unsigned int num_groups;
+ int fsel, gsel, ret;
+
+ if (len > (PINMUX_MAX_NAME * 2)) {
+ dev_err(pctldev->dev, "write too big for buffer");
+ return -EINVAL;
+ }
+
+ buf = devm_kzalloc(pctldev->dev, PINMUX_MAX_NAME * 2, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ fname = devm_kzalloc(pctldev->dev, PINMUX_MAX_NAME, GFP_KERNEL);
+ if (!fname) {
+ ret = -ENOMEM;
+ goto free_buf;
+ }
+
+ gname = devm_kzalloc(pctldev->dev, PINMUX_MAX_NAME, GFP_KERNEL);
+ if (!buf) {
+ ret = -ENOMEM;
+ goto free_fname;
+ }
+
+ ret = strncpy_from_user(buf, user_buf, PINMUX_MAX_NAME * 2);
+ if (ret < 0) {
+ dev_err(pctldev->dev, "failed to copy buffer from userspace");
+ goto free_gname;
+ }
+ buf[len-1] = '\0';
+
+ ret = sscanf(buf, "%s %s", fname, gname);
+ if (ret != 2) {
+ dev_err(pctldev->dev, "expected format: <function-name> <group-name>");
+ goto free_gname;
+ }
+
+ fsel = pinmux_func_name_to_selector(pctldev, fname);
+ if (fsel < 0) {
+ dev_err(pctldev->dev, "invalid function %s in map table\n", fname);
+ ret = -EINVAL;
+ goto free_gname;
+ }
+
+ ret = pmxops->get_function_groups(pctldev, fsel, &groups, &num_groups);
+ if (ret) {
+ dev_err(pctldev->dev, "no groups for function %d (%s)", fsel, fname);
+ goto free_gname;
+
+ }
+
+ ret = match_string(groups, num_groups, gname);
+ if (ret < 0) {
+ dev_err(pctldev->dev, "invalid group %s", gname);
+ goto free_gname;
+ }
+
+ ret = pinctrl_get_group_selector(pctldev, gname);
+ if (ret < 0) {
+ dev_err(pctldev->dev, "failed to get group selectorL %s", gname);
+ goto free_gname;
+ }
+ gsel = ret;
+
+ ret = pmxops->set_mux(pctldev, fsel, gsel);
+ if (ret) {
+ dev_err(pctldev->dev, "set_mux() failed: %d", ret);
+ goto free_gname;
+ }
+
+ return len;
+free_buf:
+ devm_kfree(pctldev->dev, buf);
+free_fname:
+ devm_kfree(pctldev->dev, fname);
+free_gname:
+ devm_kfree(pctldev->dev, gname);
+ return ret;
+}
+
+static int pinmux_select_open(struct inode *inode, struct file *file)
+{
+ return single_open(file, NULL, inode->i_private);
+}
+
+static const struct file_operations pinmux_select_ops = {
+ .owner = THIS_MODULE,
+ .open = pinmux_select_open,
+ .read = seq_read,
+ .write = pinmux_select,
+ .llseek = no_llseek,
+ .release = single_release,
+};
+
void pinmux_init_device_debugfs(struct dentry *devroot,
struct pinctrl_dev *pctldev)
{
@@ -680,6 +784,8 @@ void pinmux_init_device_debugfs(struct dentry *devroot,
devroot, pctldev, &pinmux_functions_fops);
debugfs_create_file("pinmux-pins", 0400,
devroot, pctldev, &pinmux_pins_fops);
+ debugfs_create_file("pinmux-select", 0200,
+ devroot, pctldev, &pinmux_select_ops);
}

#endif /* CONFIG_DEBUG_FS */
--
2.25.1