[PATCH] NUC900: patch for implement clk_get_rate

[PATCH] NUC900: patch for implement clk_get_rate

[Wan ZongShun]

According to Baruch's advice, I re-orgnize previous patch named
'Add platform support for nuc900 i2c driver'.

This patch is for implementing clk_get_rate, there are four clk
rates were needed to get, cpufreq,ahb,apb and external crystal.
clk_get_rate return value is for external crystal.

---
 arch/arm/mach-w90x900/clock.c |    9 +++++++
 arch/arm/mach-w90x900/clock.h |    5 ++++
 arch/arm/mach-w90x900/cpu.c   |   50 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-w90x900/clock.c b/arch/arm/mach-w90x900/clock.c
index 2c371ff..6325642 100644
--- a/arch/arm/mach-w90x900/clock.c
+++ b/arch/arm/mach-w90x900/clock.c
@@ -57,6 +57,15 @@ EXPORT_SYMBOL(clk_disable);

 unsigned long clk_get_rate(struct clk *clk)
 {
+	unsigned long flags, ret;
+
+	if (clk == NULL || IS_ERR(clk))
+		return -EPERM;
+	spin_lock_irqsave(&clocks_lock, flags);
+	ret = nuc900_get_cpuclock(&clk->cpufreq, &clk->ahbfreq, &clk->apbfreq);
+	spin_unlock_irqrestore(&clocks_lock, flags);
+	if (ret)
+		return ret;
 	return 15000000;
 }
 EXPORT_SYMBOL(clk_get_rate);
diff --git a/arch/arm/mach-w90x900/clock.h b/arch/arm/mach-w90x900/clock.h
index c56ddab..af8e04c 100644
--- a/arch/arm/mach-w90x900/clock.h
+++ b/arch/arm/mach-w90x900/clock.h
@@ -14,10 +14,15 @@

 void nuc900_clk_enable(struct clk *clk, int enable);
 void nuc900_subclk_enable(struct clk *clk, int enable);
+int nuc900_get_cpuclock(unsigned int *cpuclk_khz,
+			unsigned int *ahbclk_khz, unsigned int *apbclk_khz);

 struct clk {
 	unsigned long		cken;
 	unsigned int		enabled;
+	unsigned int		cpufreq;
+	unsigned int		ahbfreq;
+	unsigned int		apbfreq;
 	void			(*enable)(struct clk *, int enable);
 };

diff --git a/arch/arm/mach-w90x900/cpu.c b/arch/arm/mach-w90x900/cpu.c
index 642207e..c4cce24 100644
--- a/arch/arm/mach-w90x900/cpu.c
+++ b/arch/arm/mach-w90x900/cpu.c
@@ -195,6 +195,56 @@ static int __init nuc900_set_cpufreq(char *str)

 __setup("cpufreq=", nuc900_set_cpufreq);

+int nuc900_get_cpuclock(unsigned int *cpuclk_khz,
+			unsigned int *ahbclk_khz, unsigned int *apbclk_khz) {
+
+	int ahbspeed = 0, apbspeed = 0, cpuspeed = 0;
+
+	if (cpuclk_khz) {
+		cpuspeed = __raw_readl(REG_PLLCON0);
+		if (cpuspeed == PLL_200MHZ)
+			cpuspeed = 200 * 1000;
+		else if (cpuspeed == PLL_166MHZ)
+			cpuspeed = 166 * 1000;
+		else if (cpuspeed == PLL_120MHZ)
+			cpuspeed = 120 * 1000;
+		else if (cpuspeed == PLL_100MHZ)
+			cpuspeed = 100 * 1000;
+		else if (cpuspeed == PLL_66MHZ)
+			cpuspeed = 66 * 1000;
+		else {
+			printk(KERN_ERR "Can not read true cpuspeed!\n");
+			return -EPERM;
+		}
+		*cpuclk_khz = cpuspeed;
+	}
+
+	if (ahbclk_khz) {
+		ahbspeed = (__raw_readl(REG_CLKDIV) >> 24) & 0x03;
+		if (ahbspeed == AHB_CPUCLK_1_1)
+			ahbspeed = cpuspeed;
+		else if (ahbspeed == AHB_CPUCLK_1_2)
+			ahbspeed = cpuspeed / 2;
+		else {
+			printk(KERN_ERR "Can not read true ahbspeed!\n");
+			return -EPERM;
+		}
+		*ahbclk_khz = ahbspeed;
+	}
+
+	if (apbclk_khz) {
+		apbspeed = (__raw_readl(REG_CLKDIV) >> 26) & 0x03;
+		if (apbspeed == APB_AHB_1_2)
+			apbspeed = ahbspeed / 2;
+		else {
+			printk(KERN_ERR "Can not read true apbspeed!\n");
+			return -EPERM;
+		}
+		*apbclk_khz = apbspeed;
+	}
+	return 0;
+}
+
 /*Init NUC900 evb io*/

 void __init nuc900_map_io(struct map_desc *mach_desc, int mach_size)
-- 
1.6.3.3

[PATCH] NUC900: patch for implement clk_get_rate

[Russell King - ARM Linux]

On Tue, Jun 15, 2010 at 07:07:00PM +0800, Wan ZongShun wrote:
> According to Baruch's advice, I re-orgnize previous patch named
> 'Add platform support for nuc900 i2c driver'.
> 
> This patch is for implementing clk_get_rate, there are four clk
> rates were needed to get, cpufreq,ahb,apb and external crystal.
> clk_get_rate return value is for external crystal.
> 
> ---
>  arch/arm/mach-w90x900/clock.c |    9 +++++++
>  arch/arm/mach-w90x900/clock.h |    5 ++++
>  arch/arm/mach-w90x900/cpu.c   |   50 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 64 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/arm/mach-w90x900/clock.c b/arch/arm/mach-w90x900/clock.c
> index 2c371ff..6325642 100644
> --- a/arch/arm/mach-w90x900/clock.c
> +++ b/arch/arm/mach-w90x900/clock.c
> @@ -57,6 +57,15 @@ EXPORT_SYMBOL(clk_disable);
> 
>  unsigned long clk_get_rate(struct clk *clk)
>  {
> +	unsigned long flags, ret;
> +
> +	if (clk == NULL || IS_ERR(clk))
> +		return -EPERM;

Is there a reason to check for these cases?

> +	spin_lock_irqsave(&clocks_lock, flags);
> +	ret = nuc900_get_cpuclock(&clk->cpufreq, &clk->ahbfreq, &clk->apbfreq);
> +	spin_unlock_irqrestore(&clocks_lock, flags);
> +	if (ret)
> +		return ret;

Hmm, I don't follow this - and it doesn't seem to sit with the clk API
model at all well.  cpufreq/ahbfreq/apbfreq seem to only ever be
written, but never read.  I'm not sure either why every struct clk has
to have these - they seem to be separate clocks unrelated to the
struct clk that's being dealt with.

Wouldn't it make more sense to have these three as separate struct clks?

The other issue is that we're introducing an "apb_pclk" for all
primecells using drivers/amba/bus.c in order to support SoCs which gate
the APB pclk signal to individual primecells.  It sounds like this clock
would be the natural owner what you call 'apbfreq' in your patch.