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Date:   Fri, 12 Feb 2021 14:30:15 -0800
From:   Drew Fustini <drew@...gleboard.org>
To:     Linus Walleij <linus.walleij@...aro.org>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Tony Lindgren <tony@...mide.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Alexandre Belloni <alexandre.belloni@...tlin.com>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Pantelis Antoniou <pantelis.antoniou@...sulko.com>,
        Jason Kridner <jkridner@...gleboard.org>,
        Robert Nelson <robertcnelson@...gleboard.org>,
        Joe Perches <joe@...ches.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Drew Fustini <drew@...gleboard.org>
Subject: [PATCH v5 2/2] pinctrl: pinmux: Add pinmux-select debugfs file

Add "pinmux-select" to debugfs which will activate a function and group
when "<function-name group-name>" are written to the file. The write
operation pinmux_select() handles this by checking that the names map to
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 and group pinmux-i2c1-pins:

echo "pinmux-i2c1 pinmux-i2c1-pins" > pinmux-select

Signed-off-by: Drew Fustini <drew@...gleboard.org>
---
 drivers/pinctrl/pinmux.c | 99 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 99 insertions(+)

diff --git a/drivers/pinctrl/pinmux.c b/drivers/pinctrl/pinmux.c
index c651b2db0925..c16a6167ac3a 100644
--- a/drivers/pinctrl/pinmux.c
+++ b/drivers/pinctrl/pinmux.c
@@ -673,6 +673,103 @@ void pinmux_show_setting(struct seq_file *s,
 DEFINE_SHOW_ATTRIBUTE(pinmux_functions);
 DEFINE_SHOW_ATTRIBUTE(pinmux_pins);
 
+#define PINMUX_SELECT_MAX 128
+static ssize_t pinmux_select(struct file *file, const char __user *user_buf,
+				   size_t len, loff_t *ppos)
+{
+	const char *usage =
+		"usage: echo '<function-name> <group-name>' > pinmux-select";
+	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_SELECT_MAX) {
+		dev_err(pctldev->dev, "write too big for buffer");
+		return -EINVAL;
+	}
+
+	buf = kzalloc(PINMUX_SELECT_MAX, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = strncpy_from_user(buf, user_buf, PINMUX_SELECT_MAX);
+	if (ret < 0) {
+		dev_err(pctldev->dev, "failed to copy buffer from userspace");
+		goto free_buf;
+	}
+	buf[len-1] = '\0';
+
+	fname = strstrip(buf);
+	if (*fname == '\0') {
+		dev_err(pctldev->dev, usage);
+		ret = -EINVAL;
+		goto free_buf;
+	}
+
+	gname = strchr(fname, ' ');
+	if (!gname) {
+		dev_err(pctldev->dev, usage);
+		ret = -EINVAL;
+		goto free_buf;
+	}
+	*gname++ = '\0';
+
+	fsel = pinmux_func_name_to_selector(pctldev, fname);
+	if (fsel < 0) {
+		dev_err(pctldev->dev, "invalid function %s in map table\n", fname);
+		ret = fsel;
+		goto free_buf;
+	}
+
+	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_buf;
+	}
+
+	ret = match_string(groups, num_groups, gname);
+	if (ret < 0) {
+		dev_err(pctldev->dev, "invalid group %s", gname);
+		goto free_buf;
+	}
+
+	gsel = pinctrl_get_group_selector(pctldev, gname);
+	if (gsel < 0) {
+		dev_err(pctldev->dev, "failed to get group selector for %s", gname);
+		ret = gsel;
+		goto free_buf;
+	}
+
+	ret = pmxops->set_mux(pctldev, fsel, gsel);
+	if (ret) {
+		dev_err(pctldev->dev, "set_mux() failed: %d", ret);
+		goto free_buf;
+	}
+	ret = len;
+
+free_buf:
+	kfree(buf);
+
+	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,
+	.write = pinmux_select,
+	.llseek = no_llseek,
+	.release = single_release,
+};
+
 void pinmux_init_device_debugfs(struct dentry *devroot,
 			 struct pinctrl_dev *pctldev)
 {
@@ -680,6 +777,8 @@ void pinmux_init_device_debugfs(struct dentry *devroot,
 			    devroot, pctldev, &pinmux_functions_fops);
 	debugfs_create_file("pinmux-pins", 0444,
 			    devroot, pctldev, &pinmux_pins_fops);
+	debugfs_create_file("pinmux-select", 0200,
+			    devroot, pctldev, &pinmux_select_ops);
 }
 
 #endif /* CONFIG_DEBUG_FS */
-- 
2.25.1

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