Commit 7d1e3bd9 authored by Jeremy Kerr's avatar Jeremy Kerr Committed by Lee Jones
Browse files

mfd: syscon: Allow reset control for syscon devices 



Simple syscon devices may require deassertion of a reset signal in order
to access their register set. Rather than requiring a custom driver to
implement this, we can use the generic "resets" specifiers to link a
reset line to the syscon.

This change adds an optional reset line to the syscon device
description, and deasserts the reset if detected.

Signed-off-by: default avatarJeremy Kerr <jk@codeconstruct.com.au>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarLee Jones <lee@kernel.org>
Link: https://lore.kernel.org/r/20230105005010.124948-3-jk@codeconstruct.com.au
parent 0f4d2619

drivers/mfd/syscon.c

+21 −6
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/platform_data/syscon.h>

#include <linux/platform_device.h>

#include <linux/regmap.h>

#include <linux/reset.h>

#include <linux/mfd/syscon.h>

#include <linux/slab.h>
@@ -31,6 +32,7 @@ static LIST_HEAD(syscon_list); 
struct syscon {

	struct device_node *np;

	struct regmap *regmap;

	struct reset_control *reset;

	struct list_head list;

};
@@ -40,7 +42,7 @@ static const struct regmap_config syscon_regmap_config = { 
	.reg_stride = 4,

};



static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)

static struct syscon *of_syscon_register(struct device_node *np, bool check_res)

{

	struct clk *clk;

	struct syscon *syscon;
@@ -50,6 +52,7 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) 
	int ret;

	struct regmap_config syscon_config = syscon_regmap_config;

	struct resource res;

	struct reset_control *reset;



	syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);

	if (!syscon)
@@ -114,7 +117,7 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) 
		goto err_regmap;

	}



	if (check_clk) {

	if (check_res) {

		clk = of_clk_get(np, 0);

		if (IS_ERR(clk)) {

			ret = PTR_ERR(clk);
@@ -124,8 +127,18 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) 
		} else {

			ret = regmap_mmio_attach_clk(regmap, clk);

			if (ret)

				goto err_attach;

				goto err_attach_clk;

		}



		reset = of_reset_control_get_optional_exclusive(np, NULL);

		if (IS_ERR(reset)) {

			ret = PTR_ERR(reset);

			goto err_attach_clk;

		}



		ret = reset_control_deassert(reset);

		if (ret)

			goto err_reset;

	}



	syscon->regmap = regmap;
@@ -137,7 +150,9 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) 


	return syscon;



err_attach:

err_reset:

	reset_control_put(reset);

err_attach_clk:

	if (!IS_ERR(clk))

		clk_put(clk);

err_clk:
@@ -150,7 +165,7 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk) 
}



static struct regmap *device_node_get_regmap(struct device_node *np,

					     bool check_clk)

					     bool check_res)

{

	struct syscon *entry, *syscon = NULL;
@@ -165,7 +180,7 @@ static struct regmap *device_node_get_regmap(struct device_node *np, 
	spin_unlock(&syscon_list_slock);



	if (!syscon)

		syscon = of_syscon_register(np, check_clk);

		syscon = of_syscon_register(np, check_res);



	if (IS_ERR(syscon))

		return ERR_CAST(syscon);