diff options
author | Sekhar Nori <nsekhar@ti.com> | 2010-07-20 16:46:49 +0530 |
---|---|---|
committer | Kevin Hilman <khilman@deeprootsystems.com> | 2010-09-24 07:40:24 -0700 |
commit | b39639b820ca64e55c39b5217773919ca7973cec (patch) | |
tree | 53b2eba184359e1aa748e40891b3fd4149228697 | |
parent | 0a477f6b8c1849701981f6e00e7afcd35af75546 (diff) | |
download | blackbird-op-linux-b39639b820ca64e55c39b5217773919ca7973cec.tar.gz blackbird-op-linux-b39639b820ca64e55c39b5217773919ca7973cec.zip |
davinci: clock: add support for setting sysclk rate
Setting sysclk rate will be useful in cases where the
sysclk is not at a fixed ratio to the PLL output but
can asynchronously be changed.
This support forms the basis of attempt to keep the AEMIF
clock constant on OMAP-L138 even as PLL0 output changes
as ARM clock is changed to save power.
This patch has been tested on OMAP-L138.
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
-rw-r--r-- | arch/arm/mach-davinci/clock.c | 73 | ||||
-rw-r--r-- | arch/arm/mach-davinci/clock.h | 5 |
2 files changed, 78 insertions, 0 deletions
diff --git a/arch/arm/mach-davinci/clock.c b/arch/arm/mach-davinci/clock.c index 5b0cb62a058f..01ba080433db 100644 --- a/arch/arm/mach-davinci/clock.c +++ b/arch/arm/mach-davinci/clock.c @@ -287,6 +287,79 @@ static unsigned long clk_sysclk_recalc(struct clk *clk) return rate; } +int davinci_set_sysclk_rate(struct clk *clk, unsigned long rate) +{ + unsigned v; + struct pll_data *pll; + unsigned long input; + unsigned ratio = 0; + + /* If this is the PLL base clock, wrong function to call */ + if (clk->pll_data) + return -EINVAL; + + /* There must be a parent... */ + if (WARN_ON(!clk->parent)) + return -EINVAL; + + /* ... the parent must be a PLL... */ + if (WARN_ON(!clk->parent->pll_data)) + return -EINVAL; + + /* ... and this clock must have a divider. */ + if (WARN_ON(!clk->div_reg)) + return -EINVAL; + + pll = clk->parent->pll_data; + + input = clk->parent->rate; + + /* If pre-PLL, source clock is before the multiplier and divider(s) */ + if (clk->flags & PRE_PLL) + input = pll->input_rate; + + if (input > rate) { + /* + * Can afford to provide an output little higher than requested + * only if maximum rate supported by hardware on this sysclk + * is known. + */ + if (clk->maxrate) { + ratio = DIV_ROUND_CLOSEST(input, rate); + if (input / ratio > clk->maxrate) + ratio = 0; + } + + if (ratio == 0) + ratio = DIV_ROUND_UP(input, rate); + + ratio--; + } + + if (ratio > PLLDIV_RATIO_MASK) + return -EINVAL; + + do { + v = __raw_readl(pll->base + PLLSTAT); + } while (v & PLLSTAT_GOSTAT); + + v = __raw_readl(pll->base + clk->div_reg); + v &= ~PLLDIV_RATIO_MASK; + v |= ratio | PLLDIV_EN; + __raw_writel(v, pll->base + clk->div_reg); + + v = __raw_readl(pll->base + PLLCMD); + v |= PLLCMD_GOSET; + __raw_writel(v, pll->base + PLLCMD); + + do { + v = __raw_readl(pll->base + PLLSTAT); + } while (v & PLLSTAT_GOSTAT); + + return 0; +} +EXPORT_SYMBOL(davinci_set_sysclk_rate); + static unsigned long clk_leafclk_recalc(struct clk *clk) { if (WARN_ON(!clk->parent)) diff --git a/arch/arm/mach-davinci/clock.h b/arch/arm/mach-davinci/clock.h index 01e36483ac3d..11099980b58b 100644 --- a/arch/arm/mach-davinci/clock.h +++ b/arch/arm/mach-davinci/clock.h @@ -70,6 +70,9 @@ #include <linux/list.h> #include <asm/clkdev.h> +#define PLLSTAT_GOSTAT BIT(0) +#define PLLCMD_GOSET BIT(0) + struct pll_data { u32 phys_base; void __iomem *base; @@ -86,6 +89,7 @@ struct clk { struct module *owner; const char *name; unsigned long rate; + unsigned long maxrate; /* H/W supported max rate */ u8 usecount; u8 lpsc; u8 gpsc; @@ -118,6 +122,7 @@ struct clk { 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); extern struct platform_device davinci_wdt_device; extern void davinci_watchdog_reset(struct platform_device *); |