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: Jeremy Kerr <jk@codeconstruct.com.au>
---
v2:
* do reset control in the early of_syscon_register() path, rather than
the platform device init, which isn't used.
v3:
* use a direct reset_control_deassert rather than handling in the
regmap
---
drivers/mfd/syscon.c | 27 +++++++++++++++++++++------
1 file changed, 21 insertions(+), 6 deletions(-)
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index bdb2ce7ff03b..05e286a69dbe 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -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);
@@ -124,7 +127,17 @@ 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;
+ } else {
+ ret = reset_control_deassert(reset);
+ if (ret)
+ goto err_reset;
}
}
@@ -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);
--
2.35.1On Sun, 11 Dec 2022, Jeremy Kerr wrote:
> 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: Jeremy Kerr <jk@codeconstruct.com.au>
>
> ---
> v2:
> * do reset control in the early of_syscon_register() path, rather than
> the platform device init, which isn't used.
> v3:
> * use a direct reset_control_deassert rather than handling in the
> regmap
> ---
> drivers/mfd/syscon.c | 27 +++++++++++++++++++++------
> 1 file changed, 21 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index bdb2ce7ff03b..05e286a69dbe 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -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);
> @@ -124,7 +127,17 @@ 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;
> + } else {
> + ret = reset_control_deassert(reset);
> + if (ret)
> + goto err_reset;
> }
The else is superfluous, right?
Arnd, besides this are you happy with the patch?
--
Lee Jones [李琼斯]
Hi Lee,
> > @@ -124,7 +127,17 @@ 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;
> > + } else {
> > + ret = reset_control_deassert(reset);
> > + if (ret)
> > + goto err_reset;
> > }
>
> The else is superfluous, right?
Yep, we could move that reset_control_deassert() out of the else block.
If there are no other changes, I'll send a v4 with that.
Cheers,
Jeremy
On Thu, 05 Jan 2023, Jeremy Kerr wrote:
> Hi Lee,
>
> > > @@ -124,7 +127,17 @@ 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;
> > > + } else {
> > > + ret = reset_control_deassert(reset);
> > > + if (ret)
> > > + goto err_reset;
> > > }
> >
> > The else is superfluous, right?
>
> Yep, we could move that reset_control_deassert() out of the else block.
> If there are no other changes, I'll send a v4 with that.
I'd wait a little while to give Arnd a chance to respond.
Might save you a little work.
--
Lee Jones [李琼斯]
On Wed, Jan 4, 2023, at 18:57, Lee Jones wrote:
> On Thu, 05 Jan 2023, Jeremy Kerr wrote:
>
>> Hi Lee,
>>
>> > > @@ -124,7 +127,17 @@ 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;
>> > > + } else {
>> > > + ret = reset_control_deassert(reset);
>> > > + if (ret)
>> > > + goto err_reset;
>> > > }
>> >
>> > The else is superfluous, right?
>>
>> Yep, we could move that reset_control_deassert() out of the else block.
>> If there are no other changes, I'll send a v4 with that.
>
> I'd wait a little while to give Arnd a chance to respond.
>
> Might save you a little work.
Looks all good to me,
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
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