clk: at91: make use of syscon to share PMC registers in several drivers

The PMC block is providing several functionnalities:
 - system clk management
 - cpuidle
 - platform suspend

Replace the void __iomem *regs field by a regmap (retrieved using syscon)
so that we can later share the regmap across several drivers without
exporting a new specific API or a global void __iomem * variable.

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Stephen Boyd <sboyd@codeaurora.org>

arch/arm/mach-at91/Kconfig

@@ -104,6 +104,7 @@ config HAVE_AT91_USB_CLK
 config COMMON_CLK_AT91
 	bool
 	select COMMON_CLK
+	select MFD_SYSCON
 
 config HAVE_AT91_SMD
 	bool

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>
 
@@ -223,6 +224,7 @@ 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)
 {
@@ -238,7 +240,7 @@ 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;
 
@@ -394,16 +396,18 @@ 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;
+	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) {

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;
@@ -48,12 +49,16 @@ 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,