add new system file

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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c

 kernel/drivers/pinctrl/pinmux.c
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@@ -1,3 +1,4 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  * Core driver for the pin muxing portions of the pin control subsystem
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  *
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@@ -8,8 +9,6 @@
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  * Author: Linus Walleij <linus.walleij@linaro.org>
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  *
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  * Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
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- *
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- * License terms: GNU General Public License (GPL) version 2
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  */
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 #define pr_fmt(fmt) "pinmux core: " fmt
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@@ -72,7 +71,33 @@
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 }
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 /**
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+ * pinmux_can_be_used_for_gpio() - check if a specific pin
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+ *	is either muxed to a different function or used as gpio.
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+ *
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+ * @pctldev: the associated pin controller device
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+ * @pin: the pin number in the global pin space
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+ *
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+ * Controllers not defined as strict will always return true,
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+ * menaning that the gpio can be used.
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+ */
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+bool pinmux_can_be_used_for_gpio(struct pinctrl_dev *pctldev, unsigned pin)
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+{
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+	struct pin_desc *desc = pin_desc_get(pctldev, pin);
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+	const struct pinmux_ops *ops = pctldev->desc->pmxops;
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+
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+	/* Can't inspect pin, assume it can be used */
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+	if (!desc || !ops)
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+		return true;
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+
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+	if (ops->strict && desc->mux_usecount)
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+		return false;
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+
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+	return !(ops->strict && !!desc->gpio_owner);
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+}
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+
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+/**
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  * pin_request() - request a single pin to be muxed in, typically for GPIO
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+ * @pctldev: the associated pin controller device
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  * @pin: the pin number in the global pin space
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  * @owner: a representation of the owner of this pin; typically the device
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  *	name that controls its mux function, or the requested GPIO name
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@@ -231,6 +256,7 @@
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  * @pctldev: pin controller device affected
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  * @pin: the pin to mux in for GPIO
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  * @range: the applicable GPIO range
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+ * @gpio: number of requested GPIO
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  */
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 int pinmux_request_gpio(struct pinctrl_dev *pctldev,
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 			struct pinctrl_gpio_range *range,
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@@ -644,37 +670,16 @@
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 		   setting->data.mux.func);
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 }
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-static int pinmux_functions_open(struct inode *inode, struct file *file)
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-{
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-	return single_open(file, pinmux_functions_show, inode->i_private);
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-}
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-
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-static int pinmux_pins_open(struct inode *inode, struct file *file)
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-{
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-	return single_open(file, pinmux_pins_show, inode->i_private);
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-}
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-
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-static const struct file_operations pinmux_functions_ops = {
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-	.open		= pinmux_functions_open,
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-	.read		= seq_read,
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-	.llseek		= seq_lseek,
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-	.release	= single_release,
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-};
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-
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-static const struct file_operations pinmux_pins_ops = {
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-	.open		= pinmux_pins_open,
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-	.read		= seq_read,
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-	.llseek		= seq_lseek,
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-	.release	= single_release,
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-};
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+DEFINE_SHOW_ATTRIBUTE(pinmux_functions);
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+DEFINE_SHOW_ATTRIBUTE(pinmux_pins);
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 void pinmux_init_device_debugfs(struct dentry *devroot,
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 			 struct pinctrl_dev *pctldev)
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 {
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 	debugfs_create_file("pinmux-functions", S_IFREG | S_IRUGO,
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-			    devroot, pctldev, &pinmux_functions_ops);
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+			    devroot, pctldev, &pinmux_functions_fops);
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 	debugfs_create_file("pinmux-pins", S_IFREG | S_IRUGO,
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-			    devroot, pctldev, &pinmux_pins_ops);
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+			    devroot, pctldev, &pinmux_pins_fops);
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 }
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 #endif /* CONFIG_DEBUG_FS */
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@@ -742,7 +747,7 @@
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 /**
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  * pinmux_generic_get_function() - returns a function based on the number
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  * @pctldev: pin controller device
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- * @group_selector: function number
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+ * @selector: function number
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  */
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 struct function_desc *pinmux_generic_get_function(struct pinctrl_dev *pctldev,
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 						  unsigned int selector)