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clk: rockchip: rk3308: Add support for SCLK_RTC32K clock

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Add support to get and set the SCLK_RTC32K clock rate.

Signed-off-by: Finley Xiao <finley.xiao@rock-chips.com>
[jonas@kwiboo.se: Update commit message]
Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>
This commit is contained in:
Finley Xiao 2024-04-08 18:14:04 +00:00 committed by Kever Yang
parent 314992516f
commit d3e35e71ec
2 changed files with 109 additions and 0 deletions
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14
arch/arm/include/asm/arch-rk3308/cru_rk3308.h
View File

@ -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,

95
drivers/clk/rockchip/clk_rk3308.c
View File

@ -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;
}