From 518d4709f1961539a64f5d5f9b5b842824c0d971 Mon Sep 17 00:00:00 2001 From: Tony Prisk Date: Mon, 13 May 2013 20:20:59 +1200 Subject: clk: vt8500: Add support for clocks on the WM8850 SoCs The WM8850 has a different PLL clock to the previous versions. This patch adds support for the WM8850-style PLL clocks. Signed-off-by: Tony Prisk Signed-off-by: Mike Turquette --- drivers/clk/clk-vt8500.c | 71 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 71 insertions(+) (limited to 'drivers/clk/clk-vt8500.c') diff --git a/drivers/clk/clk-vt8500.c b/drivers/clk/clk-vt8500.c index debf688afa8e..6d5b6e901b96 100644 --- a/drivers/clk/clk-vt8500.c +++ b/drivers/clk/clk-vt8500.c @@ -42,6 +42,7 @@ struct clk_device { #define PLL_TYPE_VT8500 0 #define PLL_TYPE_WM8650 1 #define PLL_TYPE_WM8750 2 +#define PLL_TYPE_WM8850 3 struct clk_pll { struct clk_hw hw; @@ -327,6 +328,15 @@ CLK_OF_DECLARE(vt8500_device, "via,vt8500-device-clock", vtwm_device_clk_init); #define WM8750_BITS_TO_VAL(f, m, d1, d2) \ ((f << 24) | ((m - 1) << 16) | ((d1 - 1) << 8) | d2) +/* Helper macros for PLL_WM8850 */ +#define WM8850_PLL_MUL(x) ((((x >> 16) & 0x7F) + 1) * 2) +#define WM8850_PLL_DIV(x) ((((x >> 8) & 1) + 1) * (1 << (x & 3))) + +#define WM8850_BITS_TO_FREQ(r, m, d1, d2) \ + (r * ((m + 1) * 2) / ((d1+1) * (1 << d2))) + +#define WM8850_BITS_TO_VAL(m, d1, d2) \ + ((((m / 2) - 1) << 16) | ((d1 - 1) << 8) | d2) static void vt8500_find_pll_bits(unsigned long rate, unsigned long parent_rate, u32 *multiplier, u32 *prediv) @@ -466,6 +476,49 @@ static void wm8750_find_pll_bits(unsigned long rate, unsigned long parent_rate, *divisor2 = best_div2; } +static void wm8850_find_pll_bits(unsigned long rate, unsigned long parent_rate, + u32 *multiplier, u32 *divisor1, u32 *divisor2) +{ + u32 mul, div1, div2; + u32 best_mul, best_div1, best_div2; + unsigned long tclk, rate_err, best_err; + + best_err = (unsigned long)-1; + + /* Find the closest match (lower or equal to requested) */ + for (div1 = 1; div1 >= 0; div1--) + for (div2 = 3; div2 >= 0; div2--) + for (mul = 0; mul <= 127; mul++) { + tclk = parent_rate * ((mul + 1) * 2) / + ((div1 + 1) * (1 << div2)); + if (tclk > rate) + continue; + /* error will always be +ve */ + rate_err = rate - tclk; + if (rate_err == 0) { + *multiplier = mul; + *divisor1 = div1; + *divisor2 = div2; + return; + } + + if (rate_err < best_err) { + best_err = rate_err; + best_mul = mul; + best_div1 = div1; + best_div2 = div2; + } + } + + /* if we got here, it wasn't an exact match */ + pr_warn("%s: requested rate %lu, found rate %lu\n", __func__, rate, + rate - best_err); + + *multiplier = best_mul; + *divisor1 = best_div1; + *divisor2 = best_div2; +} + static int vtwm_pll_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long parent_rate) { @@ -489,6 +542,10 @@ static int vtwm_pll_set_rate(struct clk_hw *hw, unsigned long rate, wm8750_find_pll_bits(rate, parent_rate, &filter, &mul, &div1, &div2); pll_val = WM8750_BITS_TO_VAL(filter, mul, div1, div2); break; + case PLL_TYPE_WM8850: + wm8850_find_pll_bits(rate, parent_rate, &mul, &div1, &div2); + pll_val = WM8850_BITS_TO_VAL(mul, div1, div2); + break; default: pr_err("%s: invalid pll type\n", __func__); return 0; @@ -525,6 +582,10 @@ static long vtwm_pll_round_rate(struct clk_hw *hw, unsigned long rate, wm8750_find_pll_bits(rate, *prate, &filter, &mul, &div1, &div2); round_rate = WM8750_BITS_TO_FREQ(*prate, mul, div1, div2); break; + case PLL_TYPE_WM8850: + wm8850_find_pll_bits(rate, *prate, &mul, &div1, &div2); + round_rate = WM8850_BITS_TO_FREQ(*prate, mul, div1, div2); + break; default: round_rate = 0; } @@ -552,6 +613,10 @@ static unsigned long vtwm_pll_recalc_rate(struct clk_hw *hw, pll_freq = parent_rate * WM8750_PLL_MUL(pll_val); pll_freq /= WM8750_PLL_DIV(pll_val); break; + case PLL_TYPE_WM8850: + pll_freq = parent_rate * WM8850_PLL_MUL(pll_val); + pll_freq /= WM8850_PLL_DIV(pll_val); + break; default: pll_freq = 0; } @@ -628,6 +693,12 @@ static void __init wm8750_pll_init(struct device_node *node) } CLK_OF_DECLARE(wm8750_pll, "wm,wm8750-pll-clock", wm8750_pll_init); +static void __init wm8850_pll_init(struct device_node *node) +{ + vtwm_pll_clk_init(node, PLL_TYPE_WM8850); +} +CLK_OF_DECLARE(wm8850_pll, "wm,wm8850-pll-clock", wm8850_pll_init); + void __init vtwm_clk_init(void __iomem *base) { if (!base) -- cgit v1.2.3-70-g09d2 From 65f2c58f0f44403aa64eccc14f3a0a74d721fe7e Mon Sep 17 00:00:00 2001 From: Tony Prisk Date: Mon, 13 May 2013 20:21:00 +1200 Subject: clk: vt8500: Remove unnecessary divisor adjustment in vtwm_dclk_set_rate() The divisor adjustment code to ensure that a divisor is not rounded down, thereby giving a rate higher than requested, is unnecessary and in some instances results in the actual rate being much lower than requested due to rounding errors. The test is already performed in vtwm_dclk_round_rate(), which is always called when clk_set_rate is called. Due to rounding errors in the line: divisor = parent_rate / rate (clk-vt8500.c:160) we will sometimes end up adjusting the divisor twice - first in round_rate and then again in set_rate. This patch removes the test/adjustment in vtwm_dclk_set_rate. Signed-off-by: Tony Prisk Signed-off-by: Mike Turquette --- drivers/clk/clk-vt8500.c | 4 ---- 1 file changed, 4 deletions(-) (limited to 'drivers/clk/clk-vt8500.c') diff --git a/drivers/clk/clk-vt8500.c b/drivers/clk/clk-vt8500.c index 6d5b6e901b96..d8fd085719bf 100644 --- a/drivers/clk/clk-vt8500.c +++ b/drivers/clk/clk-vt8500.c @@ -157,10 +157,6 @@ static int vt8500_dclk_set_rate(struct clk_hw *hw, unsigned long rate, divisor = parent_rate / rate; - /* If prate / rate would be decimal, incr the divisor */ - if (rate * divisor < parent_rate) - divisor++; - if (divisor == cdev->div_mask + 1) divisor = 0; -- cgit v1.2.3-70-g09d2