davinci: am18x/da850/omap-l138: keep async clock constant with cpufreq

Keep PLL0 SYSCLK3 at a constant rate of 100MHz. This enables the AEMIF
timing to remain valid even as the PLL0 output is changed by cpufreq
driver to save power.

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

3 files changed, 11 insertions, 3 deletions

diff --git a/arch/arm/mach-davinci/board-da850-evm.c b/arch/arm/mach-davinci/board-da850-evm.c
index f5f947257011..c2800a98c49d 100644
--- a/arch/arm/mach-davinci/board-da850-evm.c
+++ b/arch/arm/mach-davinci/board-da850-evm.c
@@ -787,7 +787,7 @@ static __init void da850_evm_init(void)
         if (ret)
                 pr_warning("da850_evm_init: rtc setup failed: %d\n", ret);
 
-        ret = da850_register_cpufreq();
+        ret = da850_register_cpufreq("pll0_sysclk3");
         if (ret)
                 pr_warning("da850_evm_init: cpufreq registration failed: %d\n",
                                 ret);
diff --git a/arch/arm/mach-davinci/da850.c b/arch/arm/mach-davinci/da850.c
index 6932d804556b..5af7cfb1447e 100644
--- a/arch/arm/mach-davinci/da850.c
+++ b/arch/arm/mach-davinci/da850.c
@@ -86,6 +86,8 @@ static struct clk pll0_sysclk3 = {
         .parent         = &pll0_clk,
         .flags          = CLK_PLL,
         .div_reg        = PLLDIV3,
+        .set_rate       = davinci_set_sysclk_rate,
+        .maxrate        = 100000000,
 };
 
 static struct clk pll0_sysclk4 = {
@@ -929,10 +931,16 @@ static struct platform_device da850_cpufreq_device = {
         .dev = {
                 .platform_data  = &cpufreq_info,
         },
+        .id = -1,
 };
 
-int __init da850_register_cpufreq(void)
+int __init da850_register_cpufreq(char *async_clk)
 {
+        /* cpufreq driver can help keep an "async" clock constant */
+        if (async_clk)
+                clk_add_alias("async", da850_cpufreq_device.name,
+                                                        async_clk, NULL);
+
         return platform_device_register(&da850_cpufreq_device);
 }
 
diff --git a/arch/arm/mach-davinci/include/mach/da8xx.h b/arch/arm/mach-davinci/include/mach/da8xx.h
index 3c07059f526e..2c3f41897c17 100644
--- a/arch/arm/mach-davinci/include/mach/da8xx.h
+++ b/arch/arm/mach-davinci/include/mach/da8xx.h
@@ -78,7 +78,7 @@ int da8xx_register_lcdc(struct da8xx_lcdc_platform_data *pdata);
 int da8xx_register_mmcsd0(struct davinci_mmc_config *config);
 void __init da8xx_register_mcasp(int id, struct snd_platform_data *pdata);
 int da8xx_register_rtc(void);
-int da850_register_cpufreq(void);
+int da850_register_cpufreq(char *async_clk);
 int da8xx_register_cpuidle(void);
 void __iomem * __init da8xx_get_mem_ctlr(void);
 int da850_register_pm(struct platform_device *pdev);