[1/2] mfd: syscon: Support physical regmap bus
diff mbox series

Message ID 96d444cd73239e0166316bd8f44082031cf72491.1587088646.git.baolin.wang7@gmail.com
State New, archived
Headers show
Series
  • Add new reg_update_bits() support
Related show

Commit Message

Baolin Wang April 17, 2020, 2:14 a.m. UTC
Some platforms such as Spreadtrum platform, define a special method to
update bits of the registers instead of reading and writing, which means
we should use a physical regmap bus to define the reg_update_bits()
operation instead of the MMIO regmap bus.

Thus add a new helper for the syscon driver to allow to register a physical
regmap bus to support this new requirement.

Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
---
 drivers/mfd/syscon.c       | 23 +++++++++++++++++++++--
 include/linux/mfd/syscon.h |  7 +++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

Comments

Lee Jones April 24, 2020, 8:11 a.m. UTC | #1
On Fri, 17 Apr 2020, Baolin Wang wrote:

> Some platforms such as Spreadtrum platform, define a special method to
> update bits of the registers instead of reading and writing, which means
> we should use a physical regmap bus to define the reg_update_bits()
> operation instead of the MMIO regmap bus.
> 
> Thus add a new helper for the syscon driver to allow to register a physical
> regmap bus to support this new requirement.
> 
> Signed-off-by: Baolin Wang <baolin.wang7@gmail.com>
> ---
>  drivers/mfd/syscon.c       | 23 +++++++++++++++++++++--
>  include/linux/mfd/syscon.h |  7 +++++++
>  2 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> index 3a97816d0cba..92bfe87038ca 100644
> --- a/drivers/mfd/syscon.c
> +++ b/drivers/mfd/syscon.c
> @@ -24,6 +24,7 @@
>  #include <linux/slab.h>
>  
>  static struct platform_driver syscon_driver;
> +static struct regmap_bus *syscon_phy_regmap_bus;
>  
>  static DEFINE_SPINLOCK(syscon_list_slock);
>  static LIST_HEAD(syscon_list);
> @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
>  	syscon_config.val_bits = reg_io_width * 8;
>  	syscon_config.max_register = resource_size(&res) - reg_io_width;
>  
> -	regmap = regmap_init_mmio(NULL, base, &syscon_config);
> +	 /*
> +	  * The Spreadtrum syscon need register a real physical regmap bus
> +	  * with new atomic bits updating operation instead of using
> +	  * read-modify-write.
> +	  */
> +	if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> +	    of_device_is_compatible(np, "sprd,atomic-syscon") &&

Please find a more generic way of supporting your use-case.  This is a
generic driver, and as such I am vehemently against adding any sort of
vendor specific code in here.

> +	    syscon_phy_regmap_bus)
> +		regmap = regmap_init(NULL, syscon_phy_regmap_bus, base,
> +				     &syscon_config);
> +	else
> +		regmap = regmap_init_mmio(NULL, base, &syscon_config);
Arnd Bergmann April 24, 2020, 8:24 a.m. UTC | #2
On Fri, Apr 24, 2020 at 10:11 AM Lee Jones <lee.jones@linaro.org> wrote:
> On Fri, 17 Apr 2020, Baolin Wang wrote:
> > @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
> >       syscon_config.val_bits = reg_io_width * 8;
> >       syscon_config.max_register = resource_size(&res) - reg_io_width;
> >
> > -     regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > +      /*
> > +       * The Spreadtrum syscon need register a real physical regmap bus
> > +       * with new atomic bits updating operation instead of using
> > +       * read-modify-write.
> > +       */
> > +     if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> > +         of_device_is_compatible(np, "sprd,atomic-syscon") &&
>
> Please find a more generic way of supporting your use-case.  This is a
> generic driver, and as such I am vehemently against adding any sort of
> vendor specific code in here.

I suggested doing it this way, as all alternatives seemed worse than this.

        Arnd
Lee Jones April 24, 2020, 8:32 a.m. UTC | #3
On Fri, 24 Apr 2020, Arnd Bergmann wrote:

> On Fri, Apr 24, 2020 at 10:11 AM Lee Jones <lee.jones@linaro.org> wrote:
> > On Fri, 17 Apr 2020, Baolin Wang wrote:
> > > @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
> > >       syscon_config.val_bits = reg_io_width * 8;
> > >       syscon_config.max_register = resource_size(&res) - reg_io_width;
> > >
> > > -     regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > > +      /*
> > > +       * The Spreadtrum syscon need register a real physical regmap bus
> > > +       * with new atomic bits updating operation instead of using
> > > +       * read-modify-write.
> > > +       */
> > > +     if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> > > +         of_device_is_compatible(np, "sprd,atomic-syscon") &&
> >
> > Please find a more generic way of supporting your use-case.  This is a
> > generic driver, and as such I am vehemently against adding any sort of
> > vendor specific code in here.
> 
> I suggested doing it this way, as all alternatives seemed worse than this.

If we're using a registration function (could probably be swapped out
for or accompanied by a Device Tree property) anyway, then why conduct
the vendor platform checks?
Baolin Wang April 24, 2020, 8:42 a.m. UTC | #4
On Fri, Apr 24, 2020 at 4:32 PM Lee Jones <lee.jones@linaro.org> wrote:
>
> On Fri, 24 Apr 2020, Arnd Bergmann wrote:
>
> > On Fri, Apr 24, 2020 at 10:11 AM Lee Jones <lee.jones@linaro.org> wrote:
> > > On Fri, 17 Apr 2020, Baolin Wang wrote:
> > > > @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
> > > >       syscon_config.val_bits = reg_io_width * 8;
> > > >       syscon_config.max_register = resource_size(&res) - reg_io_width;
> > > >
> > > > -     regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > > > +      /*
> > > > +       * The Spreadtrum syscon need register a real physical regmap bus
> > > > +       * with new atomic bits updating operation instead of using
> > > > +       * read-modify-write.
> > > > +       */
> > > > +     if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> > > > +         of_device_is_compatible(np, "sprd,atomic-syscon") &&
> > >
> > > Please find a more generic way of supporting your use-case.  This is a
> > > generic driver, and as such I am vehemently against adding any sort of
> > > vendor specific code in here.
> >
> > I suggested doing it this way, as all alternatives seemed worse than this.
>
> If we're using a registration function (could probably be swapped out
> for or accompanied by a Device Tree property) anyway, then why conduct
> the vendor platform checks?

Actually I've send out the v3 patch according to Arnd's suggestion. In
v3 patch, I removed the registration function, but we agreed that
adding the vendor specific support in the syscon driver seems a better
way than others.
Baolin Wang April 24, 2020, 8:43 a.m. UTC | #5
On Fri, Apr 24, 2020 at 4:42 PM Baolin Wang <baolin.wang7@gmail.com> wrote:
>
> On Fri, Apr 24, 2020 at 4:32 PM Lee Jones <lee.jones@linaro.org> wrote:
> >
> > On Fri, 24 Apr 2020, Arnd Bergmann wrote:
> >
> > > On Fri, Apr 24, 2020 at 10:11 AM Lee Jones <lee.jones@linaro.org> wrote:
> > > > On Fri, 17 Apr 2020, Baolin Wang wrote:
> > > > > @@ -106,14 +107,25 @@ static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
> > > > >       syscon_config.val_bits = reg_io_width * 8;
> > > > >       syscon_config.max_register = resource_size(&res) - reg_io_width;
> > > > >
> > > > > -     regmap = regmap_init_mmio(NULL, base, &syscon_config);
> > > > > +      /*
> > > > > +       * The Spreadtrum syscon need register a real physical regmap bus
> > > > > +       * with new atomic bits updating operation instead of using
> > > > > +       * read-modify-write.
> > > > > +       */
> > > > > +     if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
> > > > > +         of_device_is_compatible(np, "sprd,atomic-syscon") &&
> > > >
> > > > Please find a more generic way of supporting your use-case.  This is a
> > > > generic driver, and as such I am vehemently against adding any sort of
> > > > vendor specific code in here.
> > >
> > > I suggested doing it this way, as all alternatives seemed worse than this.
> >
> > If we're using a registration function (could probably be swapped out
> > for or accompanied by a Device Tree property) anyway, then why conduct
> > the vendor platform checks?
>
> Actually I've send out the v3 patch according to Arnd's suggestion. In
> v3 patch, I removed the registration function, but we agreed that
> adding the vendor specific support in the syscon driver seems a better
> way than others.

Sorry, I forgot the link:
https://lore.kernel.org/patchwork/patch/1228160/

Patch
diff mbox series

diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
index 3a97816d0cba..92bfe87038ca 100644
--- a/drivers/mfd/syscon.c
+++ b/drivers/mfd/syscon.c
@@ -24,6 +24,7 @@ 
 #include <linux/slab.h>
 
 static struct platform_driver syscon_driver;
+static struct regmap_bus *syscon_phy_regmap_bus;
 
 static DEFINE_SPINLOCK(syscon_list_slock);
 static LIST_HEAD(syscon_list);
@@ -106,14 +107,25 @@  static struct syscon *of_syscon_register(struct device_node *np, bool check_clk)
 	syscon_config.val_bits = reg_io_width * 8;
 	syscon_config.max_register = resource_size(&res) - reg_io_width;
 
-	regmap = regmap_init_mmio(NULL, base, &syscon_config);
+	 /*
+	  * The Spreadtrum syscon need register a real physical regmap bus
+	  * with new atomic bits updating operation instead of using
+	  * read-modify-write.
+	  */
+	if (IS_ENABLED(CONFIG_ARCH_SPRD) &&
+	    of_device_is_compatible(np, "sprd,atomic-syscon") &&
+	    syscon_phy_regmap_bus)
+		regmap = regmap_init(NULL, syscon_phy_regmap_bus, base,
+				     &syscon_config);
+	else
+		regmap = regmap_init_mmio(NULL, base, &syscon_config);
 	if (IS_ERR(regmap)) {
 		pr_err("regmap init failed\n");
 		ret = PTR_ERR(regmap);
 		goto err_regmap;
 	}
 
-	if (check_clk) {
+	if (check_clk && !syscon_phy_regmap_bus) {
 		clk = of_clk_get(np, 0);
 		if (IS_ERR(clk)) {
 			ret = PTR_ERR(clk);
@@ -172,6 +184,13 @@  static struct regmap *device_node_get_regmap(struct device_node *np,
 	return syscon->regmap;
 }
 
+void syscon_register_phys_regmap_bus(struct regmap_bus *phy_regmap_bus)
+{
+	if (phy_regmap_bus)
+		syscon_phy_regmap_bus = phy_regmap_bus;
+}
+EXPORT_SYMBOL_GPL(syscon_register_phys_regmap_bus);
+
 struct regmap *device_node_to_regmap(struct device_node *np)
 {
 	return device_node_get_regmap(np, false);
diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
index 7f20e9b502a5..fbc2a2f0f414 100644
--- a/include/linux/mfd/syscon.h
+++ b/include/linux/mfd/syscon.h
@@ -13,6 +13,7 @@ 
 
 #include <linux/err.h>
 #include <linux/errno.h>
+#include <linux/regmap.h>
 
 struct device_node;
 
@@ -28,6 +29,7 @@  extern struct regmap *syscon_regmap_lookup_by_phandle_args(
 					const char *property,
 					int arg_count,
 					unsigned int *out_args);
+extern void syscon_register_phys_regmap_bus(struct regmap_bus *phy_regmap_bus);
 #else
 static inline struct regmap *device_node_to_regmap(struct device_node *np)
 {
@@ -59,6 +61,11 @@  static inline struct regmap *syscon_regmap_lookup_by_phandle_args(
 {
 	return ERR_PTR(-ENOTSUPP);
 }
+
+static inline void
+syscon_register_phys_regmap_bus(struct regmap_bus *phy_regmap_bus)
+{
+}
 #endif
 
 #endif /* __LINUX_MFD_SYSCON_H__ */