[PATCH v2] mfd: syscon: Decouple syscon interface from platform devices
Boris BREZILLON
boris.brezillon at free-electrons.com
Fri Sep 5 01:14:09 PDT 2014
On Thu, 04 Sep 2014 10:15:27 +0530
Pankaj Dubey <pankaj.dubey at samsung.com> wrote:
> Hi Boris,
>
> On Wednesday, September 03, 2014 Boris BREZILLON wrote,
> > To: Arnd Bergmann
> > Cc: Pankaj Dubey; kgene.kim at samsung.com; linux at arm.linux.org.uk; Alexander
> > Shiyan; naushad at samsung.com; Tomasz Figa; linux-kernel at vger.kernel.org;
> > joshi at samsung.com; linux-samsung-soc at vger.kernel.org;
> thomas.ab at samsung.com;
> > tomasz.figa at gmail.com; vikas.sajjan at samsung.com; chow.kim at samsung.com;
> > lee.jones at linaro.org; Michal Simek; linux-arm-kernel at lists.infradead.org;
> Mark
> > Brown
> > Subject: Re: [PATCH v2] mfd: syscon: Decouple syscon interface from
> platform
> > devices
> >
> > On Wed, 03 Sep 2014 15:49:04 +0200
> > Arnd Bergmann <arnd at arndb.de> wrote:
> >
> > > On Wednesday 03 September 2014 15:16:11 Boris BREZILLON wrote:
> > > > I checked that part, and it appears most of the code is already
> > > > there (see usage of regmap_attach_dev function here [1]).
> > > >
> > > > The only problem I see is that errors are still printed with
> > > > dev_err, which, AFAIK, will trigger a kernel panic if dev is NULL.
> > >
> > > Actually not:
> > >
> > > static int __dev_printk(const char *level, const struct device *dev,
> > > struct va_format *vaf) {
> > > if (!dev)
> > > return printk("%s(NULL device *): %pV", level, vaf);
> > >
> > > return dev_printk_emit(level[1] - '0', dev,
> > > "%s %s: %pV",
> > > dev_driver_string(dev), dev_name(dev),
> > > vaf); }
> > >
> >
> > My bad then (I don't know where I looked at to think NULL dev was not
> gracefully
> > handled :-)). Thanks for pointing this out.
> > Given that, I think it should work fine even with a NULL dev.
> > I'll give it a try on at91 ;-).
> >
>
> We have tested this patch, on Exynos board and found working well.
> In our use case DT based drivers such as USB Phy, SATA Phy, Watchdog are
> calling
> syscon_regmap_lookup_by APIs to get regmap handle to Exynos PMU and it
> worked
> well for these drivers.
>
> It would be great if after testing you share result here or give a
> Tested-By.
>
I eventually tested it (just required minor modifications to my PMC
code: see below).
Still, this patch is not achieving my final goal which is to remove the
global at91_pmc_base variable and make use of the syscon regmap to
implement at91 cpu idle and platform suspend.
Moreover, I'd like to remove the lock in at91_pmc struct as regmap is
already taking care of locking the resources when accessing a
register, but this requires a lot more changes.
Anyway, here is my
Tested-by: Boris Brezillon <boris.brezillon at free-electrons.com>
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index dd28e1f..7df2c9b 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -23,6 +23,7 @@ config COMMON_CLK_AT91
bool
default AT91_PMC_UNIT && USE_OF && !AT91_USE_OLD_CLK
select COMMON_CLK
+ select MFD_SYSCON
config OLD_CLK_AT91
bool
diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 524196b..fb2c0af 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -19,6 +19,7 @@
#include <linux/irqchip/chained_irq.h>
#include <linux/irqdomain.h>
#include <linux/of_irq.h>
+#include <linux/mfd/syscon.h>
#include <asm/proc-fns.h>
@@ -190,6 +191,7 @@ static const struct at91_pmc_caps sama5d3_caps = {
};
static struct at91_pmc *__init at91_pmc_init(struct device_node *np,
+ struct regmap *regmap,
void __iomem *regbase,
int virq, const struct at91_pmc_caps *caps)
{
@@ -205,7 +207,7 @@ static struct at91_pmc *__init at91_pmc_init(struct
device_node *np, return NULL;
spin_lock_init(&pmc->lock);
- pmc->regbase = regbase;
+ pmc->regmap = regmap;
pmc->virq = virq;
pmc->caps = caps;
@@ -348,16 +350,46 @@ static void __init of_at91_pmc_setup(struct
device_node *np, void (*clk_setup)(struct device_node *, struct
at91_pmc *); const struct of_device_id *clk_id;
void __iomem *regbase = of_iomap(np, 0);
+ struct regmap *regmap;
int virq;
- if (!regbase)
- return;
+ /*
+ * If the pmc compatible property does not contain the "syscon"
+ * string, patch the property so that syscon_node_to_regmap can
+ * consider it as a syscon device.
+ */
+ if (!of_device_is_compatible(np, "syscon")) {
+ struct property *newprop, *oldprop;
+
+ oldprop = of_find_property(np, "compatible", NULL);
+ if (!oldprop)
+ panic("Could not find compatible property");
+
+ newprop = kzalloc(sizeof(*newprop), GFP_KERNEL);
+ if (!newprop)
+ panic("Could not allocate compatible
property"); +
+ newprop->name = "compatible";
+ newprop->length = oldprop->length + sizeof("syscon");
+ newprop->value = kmalloc(newprop->length, GFP_KERNEL);
+ if (!newprop->value) {
+ kfree(newprop->value);
+ panic("Could not allocate compatible string");
+ }
+ memcpy(newprop->value, oldprop->value,
oldprop->length);
+ memcpy(newprop->value + oldprop->length, "syscon",
sizeof("syscon"));
+ of_update_property(np, newprop);
+ }
+
+ regmap = syscon_node_to_regmap(np);
+ if (IS_ERR(regmap))
+ panic("Could not retrieve syscon regmap");
virq = irq_of_parse_and_map(np, 0);
if (!virq)
return;
- pmc = at91_pmc_init(np, regbase, virq, caps);
+ pmc = at91_pmc_init(np, regmap, regbase, virq, caps);
if (!pmc)
return;
for_each_child_of_node(np, childnp) {
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 6c76259..49589ea 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -14,6 +14,7 @@
#include <linux/io.h>
#include <linux/irqdomain.h>
+#include <linux/regmap.h>
#include <linux/spinlock.h>
struct clk_range {
@@ -28,7 +29,7 @@ struct at91_pmc_caps {
};
struct at91_pmc {
- void __iomem *regbase;
+ struct regmap *regmap;
int virq;
spinlock_t lock;
const struct at91_pmc_caps *caps;
@@ -47,12 +48,16 @@ static inline void pmc_unlock(struct at91_pmc *pmc)
static inline u32 pmc_read(struct at91_pmc *pmc, int offset)
{
- return readl(pmc->regbase + offset);
+ unsigned int ret = 0;
+
+ regmap_read(pmc->regmap, offset, &ret);
+
+ return ret;
}
static inline void pmc_write(struct at91_pmc *pmc, int offset, u32
value) {
- writel(value, pmc->regbase + offset);
+ regmap_write(pmc->regmap, offset, value);
}
int of_at91_get_clk_range(struct device_node *np, const char *propname,
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