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Subject[RFC 05/12] clk: qcom: fix 16 bit alpha support calculation
Date
The alpha value calculation function has been written for
40 bit alpha which is not coming properly for 16 bit alpha.

Signed-off-by: Abhishek Sahu <absahu@codeaurora.org>
---
drivers/clk/qcom/clk-alpha-pll.c | 58 +++++++++++++++++++++++-----------------
1 file changed, 34 insertions(+), 24 deletions(-)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index ef24c80..3a7ec42 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -45,8 +45,11 @@
* Even though 40 bits are present, use only 32 for ease of calculation.
*/
#define ALPHA_REG_BITWIDTH 40
+#define ALPHA_REG_16BIT_WIDTH 16
#define ALPHA_BITWIDTH 32
-#define ALPHA_16BIT_MASK 0xffff
+
+#define pll_alpha_width(pll) (pll->flags & SUPPORTS_16BIT_ALPHA ? \
+ ALPHA_REG_16BIT_WIDTH : ALPHA_REG_BITWIDTH)

#define pll_mode(pll) (pll->base + pll->offsets[ALPHA_PLL_MODE])
#define pll_l(pll) (pll->base + pll->offsets[ALPHA_PLL_L_VAL])
@@ -316,13 +319,16 @@ static void clk_alpha_pll_disable(struct clk_hw *hw)
regmap_update_bits(pll->clkr.regmap, pll_mode(pll), mask, 0);
}

-static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
+static unsigned long
+alpha_pll_calc_rate(u64 prate, u32 l, u32 a, u32 alpha_width)
{
- return (prate * l) + ((prate * a) >> ALPHA_BITWIDTH);
+ return (prate * l) + ((prate * a) >>
+ (alpha_width > ALPHA_BITWIDTH ? ALPHA_BITWIDTH : alpha_width));
}

static unsigned long
-alpha_pll_round_rate(unsigned long rate, unsigned long prate, u32 *l, u64 *a)
+alpha_pll_round_rate(unsigned long rate, unsigned long prate, u32 *l, u64 *a,
+ u32 alpha_width)
{
u64 remainder;
u64 quotient;
@@ -337,14 +343,16 @@ static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
}

/* Upper ALPHA_BITWIDTH bits of Alpha */
- quotient = remainder << ALPHA_BITWIDTH;
+ quotient = remainder << (alpha_width > ALPHA_BITWIDTH ?
+ ALPHA_BITWIDTH : alpha_width);
+
remainder = do_div(quotient, prate);

if (remainder)
quotient++;

*a = quotient;
- return alpha_pll_calc_rate(prate, *l, *a);
+ return alpha_pll_calc_rate(prate, *l, *a, alpha_width);
}

static const struct pll_vco *
@@ -363,26 +371,26 @@ static unsigned long alpha_pll_calc_rate(u64 prate, u32 l, u32 a)
static unsigned long
clk_alpha_pll_recalc_rate(struct clk_hw *hw, unsigned long parent_rate)
{
- u32 l, low, high, ctl;
- u64 a = 0, prate = parent_rate;
struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
+ u32 l, low, high, ctl, alpha_width = pll_alpha_width(pll);
+ u64 a = 0, prate = parent_rate;

regmap_read(pll->clkr.regmap, pll_l(pll), &l);

regmap_read(pll->clkr.regmap, pll_user_ctl(pll), &ctl);
if (ctl & PLL_ALPHA_EN) {
regmap_read(pll->clkr.regmap, pll_alpha(pll), &low);
- if (pll->flags & SUPPORTS_16BIT_ALPHA) {
- a = low & ALPHA_16BIT_MASK;
- } else {
+ if (alpha_width > ALPHA_BITWIDTH) {
regmap_read(pll->clkr.regmap, pll_alpha_u(pll),
&high);
- a = (u64)high << 32 | low;
- a >>= ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH;
+ a = (u64)high << ALPHA_BITWIDTH | low;
+ a >>= alpha_width - ALPHA_BITWIDTH;
+ } else {
+ a = low;
}
}

- return alpha_pll_calc_rate(prate, l, a);
+ return alpha_pll_calc_rate(prate, l, a, alpha_width);
}

static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -390,10 +398,10 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,
{
struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
const struct pll_vco *vco;
- u32 l;
+ u32 l, alpha_width = pll_alpha_width(pll);
u64 a;

- rate = alpha_pll_round_rate(rate, prate, &l, &a);
+ rate = alpha_pll_round_rate(rate, prate, &l, &a, alpha_width);
vco = alpha_pll_find_vco(pll, rate);
if (!vco) {
pr_err("alpha pll not in a valid vco range\n");
@@ -402,14 +410,16 @@ static int clk_alpha_pll_set_rate(struct clk_hw *hw, unsigned long rate,

regmap_write(pll->clkr.regmap, pll_l(pll), l);

- if (pll->flags & SUPPORTS_16BIT_ALPHA) {
- regmap_write(pll->clkr.regmap, pll_alpha(pll),
- a & ALPHA_16BIT_MASK);
- } else {
- a <<= (ALPHA_REG_BITWIDTH - ALPHA_BITWIDTH);
- regmap_write(pll->clkr.regmap, pll_alpha_u(pll), a >> 32);
+ if (alpha_width > ALPHA_BITWIDTH) {
+ a <<= (alpha_width - ALPHA_BITWIDTH);
+ regmap_update_bits(pll->clkr.regmap, pll_alpha_u(pll),
+ GENMASK(0, alpha_width - ALPHA_BITWIDTH - 1),
+ a >> ALPHA_BITWIDTH);
}

+ regmap_update_bits(pll->clkr.regmap, pll_alpha(pll),
+ GENMASK(0, alpha_width - 1), a);
+
regmap_update_bits(pll->clkr.regmap, pll_user_ctl(pll),
PLL_VCO_MASK << PLL_VCO_SHIFT,
vco->val << PLL_VCO_SHIFT);
@@ -424,11 +434,11 @@ static long clk_alpha_pll_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *prate)
{
struct clk_alpha_pll *pll = to_clk_alpha_pll(hw);
- u32 l;
+ u32 l, alpha_width = pll_alpha_width(pll);
u64 a;
unsigned long min_freq, max_freq;

- rate = alpha_pll_round_rate(rate, *prate, &l, &a);
+ rate = alpha_pll_round_rate(rate, *prate, &l, &a, alpha_width);
if (alpha_pll_find_vco(pll, rate))
return rate;

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation
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