From 3ff51ed8287d3d2c7899f18f0487348e3448afb5 Mon Sep 17 00:00:00 2001 From: Jon Hunter Date: Sat, 15 Dec 2012 01:35:46 -0700 Subject: ARM: OMAP4: Enhance support for DPLLs with 4X multiplier On OMAP4 devices, the ABE DPLL has an internal 4X multiplier that can be enabled or disabled in addition to the standard configurable multiplier (M) for OMAP DPLLs. When configuring the ABE DPLL the 4X multiplier is accounted for by checking to see whether it is enabled or not. However, when calculating a new rate we only check to see if the rate can be achieved with the current setting for the 4X multiplier. Enhance the round_rate() function for such DPLLs to see if the rate can be achieved with the 4X multiplier if it cannot be achieved without the 4X multiplier. This change is necessary, because when using the 32kHz clock as the source clock for the ABE DPLL, the default DPLL frequency for the ABE DPLL cannot be achieved without enabling the 4X multiplier. When using the 32kHz clock as the source clock for the ABE DPLL and attempting to lock the DPLL to 98.304MHz (default frequency), it was found that the DPLL would fail to lock if the low-power mode for the DPLL was not enabled. From reviewing boot-loader settings that configure the ABE DPLL it was found that the low-power mode is enabled when using the 32kHz clock source, however, the documentation for OMAP does not state that this is a requirement. Therefore, introduce a new function for OMAP4 devices to see if low-power mode can be enabled when calculating a new rate to ensure the DPLL will lock. New variables for the last calculated 4X multiplier and low-power setting have been added to the dpll data structure as well as variables defining the bit mask for enabling these features via the DPLL's control_reg. It is possible that we could eliminate these bit masks from the dpll data structure as these bit masks are not unique to OMAP4, if it is preferred. The function omap3_noncore_program_dpll() has been updated to avoid passing the calculated values for the multiplier (M) and divider (N) as these are stored in the clk structure. Signed-off-by: Jon Hunter Signed-off-by: Paul Walmsley --- arch/arm/mach-omap2/dpll3xxx.c | 46 +++++++++++++++++++++++++++++------------- 1 file changed, 32 insertions(+), 14 deletions(-) (limited to 'arch/arm/mach-omap2/dpll3xxx.c') diff --git a/arch/arm/mach-omap2/dpll3xxx.c b/arch/arm/mach-omap2/dpll3xxx.c index fafb28c0dcbc..2bb18838cba9 100644 --- a/arch/arm/mach-omap2/dpll3xxx.c +++ b/arch/arm/mach-omap2/dpll3xxx.c @@ -291,16 +291,13 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n) /* * _omap3_noncore_dpll_program - set non-core DPLL M,N values directly - * @clk: struct clk * of DPLL to set - * @m: DPLL multiplier to set - * @n: DPLL divider to set - * @freqsel: FREQSEL value to set + * @clk: struct clk * of DPLL to set + * @freqsel: FREQSEL value to set * - * Program the DPLL with the supplied M, N values, and wait for the DPLL to - * lock.. Returns -EINVAL upon error, or 0 upon success. + * Program the DPLL with the last M, N values calculated, and wait for + * the DPLL to lock. Returns -EINVAL upon error, or 0 upon success. */ -static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 m, u8 n, - u16 freqsel) +static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 freqsel) { struct dpll_data *dd = clk->dpll_data; u8 dco, sd_div; @@ -323,23 +320,45 @@ static int omap3_noncore_dpll_program(struct clk_hw_omap *clk, u16 m, u8 n, /* Set DPLL multiplier, divider */ v = __raw_readl(dd->mult_div1_reg); v &= ~(dd->mult_mask | dd->div1_mask); - v |= m << __ffs(dd->mult_mask); - v |= (n - 1) << __ffs(dd->div1_mask); + v |= dd->last_rounded_m << __ffs(dd->mult_mask); + v |= (dd->last_rounded_n - 1) << __ffs(dd->div1_mask); /* Configure dco and sd_div for dplls that have these fields */ if (dd->dco_mask) { - _lookup_dco(clk, &dco, m, n); + _lookup_dco(clk, &dco, dd->last_rounded_m, dd->last_rounded_n); v &= ~(dd->dco_mask); v |= dco << __ffs(dd->dco_mask); } if (dd->sddiv_mask) { - _lookup_sddiv(clk, &sd_div, m, n); + _lookup_sddiv(clk, &sd_div, dd->last_rounded_m, + dd->last_rounded_n); v &= ~(dd->sddiv_mask); v |= sd_div << __ffs(dd->sddiv_mask); } __raw_writel(v, dd->mult_div1_reg); + /* Set 4X multiplier and low-power mode */ + if (dd->m4xen_mask || dd->lpmode_mask) { + v = __raw_readl(dd->control_reg); + + if (dd->m4xen_mask) { + if (dd->last_rounded_m4xen) + v |= dd->m4xen_mask; + else + v &= ~dd->m4xen_mask; + } + + if (dd->lpmode_mask) { + if (dd->last_rounded_lpmode) + v |= dd->lpmode_mask; + else + v &= ~dd->lpmode_mask; + } + + __raw_writel(v, dd->control_reg); + } + /* We let the clock framework set the other output dividers later */ /* REVISIT: Set ramp-up delay? */ @@ -492,8 +511,7 @@ int omap3_noncore_dpll_set_rate(struct clk_hw *hw, unsigned long rate, pr_debug("%s: %s: set rate: locking rate to %lu.\n", __func__, __clk_get_name(hw->clk), rate); - ret = omap3_noncore_dpll_program(clk, dd->last_rounded_m, - dd->last_rounded_n, freqsel); + ret = omap3_noncore_dpll_program(clk, freqsel); if (!ret) new_parent = dd->clk_ref; } -- cgit v1.2.3