davinci: dm6467/T EVM: fix setting up of reference clock rate

The DM6467 and DM6467T EVMs use different reference clock
frequencies. This difference is currently supported by having
the SoC code call a public board routine which sets up the reference
clock frequency. This does not scale as more boards are added.

Instead, use the clk_set_rate() API to setup the reference clock
frequency to a different value from the board file.

Suggested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>

arch/arm/mach-davinci/board-dm646x-evm.c

@@ -719,9 +719,15 @@ static void __init cdce_clk_init(void)
 	}
 }
 
+#define DM6467T_EVM_REF_FREQ		33000000
+
 static void __init davinci_map_io(void)
 {
 	dm646x_init();
+
+	if (machine_is_davinci_dm6467tevm())
+		davinci_set_refclk_rate(DM6467T_EVM_REF_FREQ);
+
 	cdce_clk_init();
 }
 
@@ -785,17 +791,6 @@ static __init void evm_init(void)
 	soc_info->emac_pdata->phy_id = DM646X_EVM_PHY_ID;
 }
 
-#define DM646X_EVM_REF_FREQ		27000000
-#define DM6467T_EVM_REF_FREQ		33000000
-
-void __init dm646x_board_setup_refclk(struct clk *clk)
-{
-	if (machine_is_davinci_dm6467tevm())
-		clk->rate = DM6467T_EVM_REF_FREQ;
-	else
-		clk->rate = DM646X_EVM_REF_FREQ;
-}
-
 MACHINE_START(DAVINCI_DM6467_EVM, "DaVinci DM646x EVM")
 	.boot_params  = (0x80000100),
 	.map_io       = davinci_map_io,

arch/arm/mach-davinci/clock.c

@@ -368,6 +368,12 @@ static unsigned long clk_leafclk_recalc(struct clk *clk)
 	return clk->parent->rate;
 }
 
+int davinci_simple_set_rate(struct clk *clk, unsigned long rate)
+{
+	clk->rate = rate;
+	return 0;
+}
+
 static unsigned long clk_pllclk_recalc(struct clk *clk)
 {
 	u32 ctrl, mult = 1, prediv = 1, postdiv = 1;
@@ -506,6 +512,38 @@ int davinci_set_pllrate(struct pll_data *pll, unsigned int prediv,
 }
 EXPORT_SYMBOL(davinci_set_pllrate);
 
+/**
+ * davinci_set_refclk_rate() - Set the reference clock rate
+ * @rate:	The new rate.
+ *
+ * Sets the reference clock rate to a given value. This will most likely
+ * result in the entire clock tree getting updated.
+ *
+ * This is used to support boards which use a reference clock different
+ * than that used by default in <soc>.c file. The reference clock rate
+ * should be updated early in the boot process; ideally soon after the
+ * clock tree has been initialized once with the default reference clock
+ * rate (davinci_common_init()).
+ *
+ * Returns 0 on success, error otherwise.
+ */
+int davinci_set_refclk_rate(unsigned long rate)
+{
+	struct clk *refclk;
+
+	refclk = clk_get(NULL, "ref");
+	if (IS_ERR(refclk)) {
+		pr_err("%s: failed to get reference clock.\n", __func__);
+		return PTR_ERR(refclk);
+	}
+
+	clk_set_rate(refclk, rate);
+
+	clk_put(refclk);
+
+	return 0;
+}
+
 int __init davinci_clk_init(struct clk_lookup *clocks)
   {
 	struct clk_lookup *c;

arch/arm/mach-davinci/clock.h

@@ -123,6 +123,8 @@ int davinci_clk_init(struct clk_lookup *clocks);
 int davinci_set_pllrate(struct pll_data *pll, unsigned int prediv,
 				unsigned int mult, unsigned int postdiv);
 int davinci_set_sysclk_rate(struct clk *clk, unsigned long rate);
+int davinci_set_refclk_rate(unsigned long rate);
+int davinci_simple_set_rate(struct clk *clk, unsigned long rate);
 
 extern struct platform_device davinci_wdt_device;
 extern void davinci_watchdog_reset(struct platform_device *);

arch/arm/mach-davinci/dm646x.c

@@ -42,6 +42,7 @@
 /*
  * Device specific clocks
  */
+#define DM646X_REF_FREQ		27000000
 #define DM646X_AUX_FREQ		24000000
 
 static struct pll_data pll1_data = {
@@ -56,6 +57,8 @@ static struct pll_data pll2_data = {
 
 static struct clk ref_clk = {
 	.name = "ref_clk",
+	.rate = DM646X_REF_FREQ,
+	.set_rate = davinci_simple_set_rate,
 };
 
 static struct clk aux_clkin = {
@@ -901,7 +904,6 @@ int __init dm646x_init_edma(struct edma_rsv_info *rsv)
 
 void __init dm646x_init(void)
 {
-	dm646x_board_setup_refclk(&ref_clk);
 	davinci_common_init(&davinci_soc_info_dm646x);
 }
 

arch/arm/mach-davinci/include/mach/dm646x.h

@@ -15,7 +15,6 @@
 #include <mach/asp.h>
 #include <linux/i2c.h>
 #include <linux/videodev2.h>
-#include <linux/clk.h>
 #include <linux/davinci_emac.h>
 
 #define DM646X_EMAC_BASE		(0x01C80000)
@@ -31,7 +30,6 @@
 void __init dm646x_init(void);
 void __init dm646x_init_mcasp0(struct snd_platform_data *pdata);
 void __init dm646x_init_mcasp1(struct snd_platform_data *pdata);
-void __init dm646x_board_setup_refclk(struct clk *clk);
 int __init dm646x_init_edma(struct edma_rsv_info *rsv);
 
 void dm646x_video_init(void);