From: Finley Xiao <finley.x...@rock-chips.com>
Add support to get and set the SCLK_RTC32K clock rate.
Signed-off-by: Finley Xiao <finley.x...@rock-chips.com>
[jo...@kwiboo.se: Update commit message]
Signed-off-by: Jonas Karlman <jo...@kwiboo.se>
---
v2: No change
---
arch/arm/include/asm/arch-rk3308/cru_rk3308.h | 14 +++
drivers/clk/rockchip/clk_rk3308.c | 95 +++++++++++++++++++
2 files changed, 109 insertions(+)
diff --git a/arch/arm/include/asm/arch-rk3308/cru_rk3308.h
b/arch/arm/include/asm/arch-rk3308/cru_rk3308.h
index 84b63e4d5682..091ae82d7cc1 100644
--- a/arch/arm/include/asm/arch-rk3308/cru_rk3308.h
+++ b/arch/arm/include/asm/arch-rk3308/cru_rk3308.h
@@ -147,6 +147,20 @@ enum {
CORE_DIV_CON_SHIFT = 0,
CORE_DIV_CON_MASK = 0x0f << CORE_DIV_CON_SHIFT,
+ /* CRU_CLK_SEL2_CON */
+ CLK_RTC32K_SEL_SHIFT = 8,
+ CLK_RTC32K_SEL_MASK = 3 << CLK_RTC32K_SEL_SHIFT,
+ CLK_RTC32K_IO = 0,
+ CLK_RTC32K_PVTM,
+ CLK_RTC32K_FRAC_DIV,
+ CLK_RTC32K_DIV,
+
+ /* CRU_CLK_SEL3_CON */
+ CLK_RTC32K_FRAC_NUMERATOR_SHIFT = 16,
+ CLK_RTC32K_FRAC_NUMERATOR_MASK = 0xffff << 16,
+ CLK_RTC32K_FRAC_DENOMINATOR_SHIFT = 0,
+ CLK_RTC32K_FRAC_DENOMINATOR_MASK = 0xffff,
+
/* CRU_CLK_SEL5_CON */
BUS_PLL_SEL_SHIFT = 6,
BUS_PLL_SEL_MASK = 0x3 << BUS_PLL_SEL_SHIFT,
diff --git a/drivers/clk/rockchip/clk_rk3308.c
b/drivers/clk/rockchip/clk_rk3308.c
index 7755b0161118..7515fc8bb244 100644
--- a/drivers/clk/rockchip/clk_rk3308.c
+++ b/drivers/clk/rockchip/clk_rk3308.c
@@ -65,6 +65,57 @@ static struct rockchip_pll_clock rk3308_pll_clks[] = {
RK3308_MODE_CON, 6, 10, 0, NULL),
};
+/*
+ *
+ * rational_best_approximation(31415, 10000,
+ * (1 << 8) - 1, (1 << 5) - 1, &n, &d);
+ *
+ * you may look at given_numerator as a fixed point number,
+ * with the fractional part size described in given_denominator.
+ *
+ * for theoretical background, see:
+ * http://en.wikipedia.org/wiki/Continued_fraction
+ */
+static void rational_best_approximation(unsigned long given_numerator,
+ unsigned long given_denominator,
+ unsigned long max_numerator,
+ unsigned long max_denominator,
+ unsigned long *best_numerator,
+ unsigned long *best_denominator)
+{
+ unsigned long n, d, n0, d0, n1, d1;
+
+ n = given_numerator;
+ d = given_denominator;
+ n0 = 0;
+ d1 = 0;
+ n1 = 1;
+ d0 = 1;
+ for (;;) {
+ unsigned long t, a;
+
+ if (n1 > max_numerator || d1 > max_denominator) {
+ n1 = n0;
+ d1 = d0;
+ break;
+ }
+ if (d == 0)
+ break;
+ t = d;
+ a = n / d;
+ d = n % d;
+ n = t;
+ t = n0 + a * n1;
+ n0 = n1;
+ n1 = t;
+ t = d0 + a * d1;
+ d0 = d1;
+ d1 = t;
+ }
+ *best_numerator = n1;
+ *best_denominator = d1;
+}
+
static ulong rk3308_armclk_set_clk(struct rk3308_clk_priv *priv, ulong hz)
{
struct rk3308_cru *cru = priv->cru;
@@ -832,6 +883,44 @@ static ulong rk3308_crypto_set_clk(struct rk3308_clk_priv
*priv, ulong clk_id,
return rk3308_crypto_get_clk(priv, clk_id);
}
+static ulong rk3308_rtc32k_get_clk(struct rk3308_clk_priv *priv, ulong clk_id)
+{
+ struct rk3308_cru *cru = priv->cru;
+ unsigned long m, n;
+ u32 con, fracdiv;
+
+ con = readl(&cru->clksel_con[2]);
+ if ((con & CLK_RTC32K_SEL_MASK) >> CLK_RTC32K_SEL_SHIFT !=
+ CLK_RTC32K_FRAC_DIV)
+ return -EINVAL;
+
+ fracdiv = readl(&cru->clksel_con[3]);
+ m = fracdiv & CLK_RTC32K_FRAC_NUMERATOR_MASK;
+ m >>= CLK_RTC32K_FRAC_NUMERATOR_SHIFT;
+ n = fracdiv & CLK_RTC32K_FRAC_DENOMINATOR_MASK;
+ n >>= CLK_RTC32K_FRAC_DENOMINATOR_SHIFT;
+
+ return OSC_HZ * m / n;
+}
+
+static ulong rk3308_rtc32k_set_clk(struct rk3308_clk_priv *priv, ulong clk_id,
+ ulong hz)
+{
+ struct rk3308_cru *cru = priv->cru;
+ unsigned long m, n, val;
+
+ rational_best_approximation(hz, OSC_HZ,
+ GENMASK(16 - 1, 0),
+ GENMASK(16 - 1, 0),
+ &m, &n);
+ val = m << CLK_RTC32K_FRAC_NUMERATOR_SHIFT | n;
+ writel(val, &cru->clksel_con[3]);
+ rk_clrsetreg(&cru->clksel_con[2], CLK_RTC32K_SEL_MASK,
+ CLK_RTC32K_FRAC_DIV << CLK_RTC32K_SEL_SHIFT);
+
+ return rk3308_rtc32k_get_clk(priv, clk_id);
+}
+
static ulong rk3308_clk_get_rate(struct clk *clk)
{
struct rk3308_clk_priv *priv = dev_get_priv(clk->dev);
@@ -912,6 +1001,9 @@ static ulong rk3308_clk_get_rate(struct clk *clk)
case SCLK_CRYPTO_APK:
rate = rk3308_crypto_get_clk(priv, clk->id);
break;
+ case SCLK_RTC32K:
+ rate = rk3308_rtc32k_get_clk(priv, clk->id);
+ break;
default:
return -ENOENT;
}
@@ -990,6 +1082,9 @@ static ulong rk3308_clk_set_rate(struct clk *clk, ulong
rate)
case SCLK_CRYPTO_APK:
ret = rk3308_crypto_set_clk(priv, clk->id, rate);
break;
+ case SCLK_RTC32K:
+ ret = rk3308_rtc32k_set_clk(priv, clk->id, rate);
+ break;
default:
return -ENOENT;
}
--
2.43.2
