From f84d42a9cffc4ecd96f1ce3a038f841782142eb2 Mon Sep 17 00:00:00 2001 From: Vladimir Zapolskiy Date: Fri, 7 Oct 2016 04:16:55 +0300 Subject: [PATCH] clk: lpc32xx: add a quirk for PWM and MS clock dividers In common clock framework CLK_DIVIDER_ONE_BASED or'ed with CLK_DIVIDER_ALLOW_ZERO flags indicates that 1) a divider clock may be set to zero value, 2) divider's zero value is interpreted as a non-divided clock. On the LPC32xx platform clock dividers of PWM and memory card clocks comply with the first condition, but zero value means a gated clock, thus it may happen that the divider value is not updated when the clock is enabled and the clock remains gated. The change adds one-shot quirks, which check for zero value of divider on initialization and set it to a non-zero value, therefore in runtime a gate clock will work as expected. Signed-off-by: Vladimir Zapolskiy Reviewed-by: Sylvain Lemieux Signed-off-by: Stephen Boyd --- drivers/clk/nxp/clk-lpc32xx.c | 32 ++++++++++++++++++++++++++++---- 1 file changed, 28 insertions(+), 4 deletions(-) diff --git a/drivers/clk/nxp/clk-lpc32xx.c b/drivers/clk/nxp/clk-lpc32xx.c index 34c97353cdeb..5b98ff9076f3 100644 --- a/drivers/clk/nxp/clk-lpc32xx.c +++ b/drivers/clk/nxp/clk-lpc32xx.c @@ -1282,13 +1282,13 @@ static struct clk_hw_proto clk_hw_proto[LPC32XX_CLK_HW_MAX] = { LPC32XX_DEFINE_MUX(PWM1_MUX, PWMCLK_CTRL, 1, 0x1, NULL, 0), LPC32XX_DEFINE_DIV(PWM1_DIV, PWMCLK_CTRL, 4, 4, NULL, - CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ALLOW_ZERO), + CLK_DIVIDER_ONE_BASED), LPC32XX_DEFINE_GATE(PWM1_GATE, PWMCLK_CTRL, 0, 0), LPC32XX_DEFINE_COMPOSITE(PWM1, PWM1_MUX, PWM1_DIV, PWM1_GATE), LPC32XX_DEFINE_MUX(PWM2_MUX, PWMCLK_CTRL, 3, 0x1, NULL, 0), LPC32XX_DEFINE_DIV(PWM2_DIV, PWMCLK_CTRL, 8, 4, NULL, - CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ALLOW_ZERO), + CLK_DIVIDER_ONE_BASED), LPC32XX_DEFINE_GATE(PWM2_GATE, PWMCLK_CTRL, 2, 0), LPC32XX_DEFINE_COMPOSITE(PWM2, PWM2_MUX, PWM2_DIV, PWM2_GATE), @@ -1335,8 +1335,7 @@ static struct clk_hw_proto clk_hw_proto[LPC32XX_CLK_HW_MAX] = { LPC32XX_DEFINE_GATE(USB_DIV_GATE, USB_CTRL, 17, 0), LPC32XX_DEFINE_COMPOSITE(USB_DIV, _NULL, USB_DIV_DIV, USB_DIV_GATE), - LPC32XX_DEFINE_DIV(SD_DIV, MS_CTRL, 0, 4, NULL, - CLK_DIVIDER_ONE_BASED | CLK_DIVIDER_ALLOW_ZERO), + LPC32XX_DEFINE_DIV(SD_DIV, MS_CTRL, 0, 4, NULL, CLK_DIVIDER_ONE_BASED), LPC32XX_DEFINE_CLK(SD_GATE, MS_CTRL, BIT(5) | BIT(9), BIT(5) | BIT(9), 0x0, BIT(5) | BIT(9), 0x0, 0x0, clk_mask_ops), LPC32XX_DEFINE_COMPOSITE(SD, _NULL, SD_DIV, SD_GATE), @@ -1478,6 +1477,20 @@ static struct clk * __init lpc32xx_clk_register(u32 id) return clk; } +static void __init lpc32xx_clk_div_quirk(u32 reg, u32 div_mask, u32 gate) +{ + u32 val; + + regmap_read(clk_regmap, reg, &val); + + if (!(val & div_mask)) { + val &= ~gate; + val |= BIT(__ffs(div_mask)); + } + + regmap_update_bits(clk_regmap, reg, gate | div_mask, val); +} + static void __init lpc32xx_clk_init(struct device_node *np) { unsigned int i; @@ -1517,6 +1530,17 @@ static void __init lpc32xx_clk_init(struct device_node *np) return; } + /* + * Divider part of PWM and MS clocks requires a quirk to avoid + * a misinterpretation of formally valid zero value in register + * bitfield, which indicates another clock gate. Instead of + * adding complexity to a gate clock ensure that zero value in + * divider clock is never met in runtime. + */ + lpc32xx_clk_div_quirk(LPC32XX_CLKPWR_PWMCLK_CTRL, 0xf0, BIT(0)); + lpc32xx_clk_div_quirk(LPC32XX_CLKPWR_PWMCLK_CTRL, 0xf00, BIT(2)); + lpc32xx_clk_div_quirk(LPC32XX_CLKPWR_MS_CTRL, 0xf, BIT(5) | BIT(9)); + for (i = 1; i < LPC32XX_CLK_MAX; i++) { clk[i] = lpc32xx_clk_register(i); if (IS_ERR(clk[i])) { -- 2.30.2