[U-Boot] [PATCH v3 43/66] rockchip: clk: rk3368: implement MMC/SD clock reparenting

Philipp Tomsich
2017-07-28T19:22:15Z

The original clock support for MMC/SD cards on the RK3368 suffered
from a tendency to select a divider less-or-equal to the the one
giving the requested clock-rate: this can lead to higher-than-expected
(or rather: higher than supported) clock rates for the MMC/SD
communiction.

This change rewrites the MMC/SD clock generation to:
* always generate a clock less-than-or-equal to the requested clock
* support reparenting among the CPLL, GPLL and OSC24M parents to
generate the highest clock that does not exceed the requested rate

In addition to this, the Linux DTS uses HCLK_MMC/HCLK_SDMMC instead of
SCLK_MMC/SCLK_SDMMC: to match this (and to ensure that clock setup
always works), we adjust the driver appropriately.

This includes the changes from:
- rockchip: clk: rk3368: convert MMC_PLL_SEL_* definitions to shifted-value form

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

Reviewed-by: Simon Glass <sjg@chromium.org>
---

Changes in v3: None
Changes in v2: None

arch/arm/include/asm/arch-rockchip/cru_rk3368.h | 8 +-
drivers/clk/rockchip/clk_rk3368.c | 119 ++++++++++++++++++------
2 files changed, 95 insertions(+), 32 deletions(-)

diff --git a/arch/arm/include/asm/arch-rockchip/cru_rk3368.h b/arch/arm/include/asm/arch-rockchip/cru_rk3368.h
index bf09e2f..21f11e0 100644
--- a/arch/arm/include/asm/arch-rockchip/cru_rk3368.h
+++ b/arch/arm/include/asm/arch-rockchip/cru_rk3368.h
@@ -92,10 +92,10 @@ enum {
/* CLKSEL51_CON */
MMC_PLL_SEL_SHIFT = 8,
MMC_PLL_SEL_MASK = GENMASK(9, 8),
- MMC_PLL_SEL_CPLL = 0,
- MMC_PLL_SEL_GPLL,
- MMC_PLL_SEL_USBPHY_480M,
- MMC_PLL_SEL_24M,
+ MMC_PLL_SEL_CPLL = (0 << MMC_PLL_SEL_SHIFT),
+ MMC_PLL_SEL_GPLL = (1 << MMC_PLL_SEL_SHIFT),
+ MMC_PLL_SEL_USBPHY_480M = (2 << MMC_PLL_SEL_SHIFT),
+ MMC_PLL_SEL_24M = (3 << MMC_PLL_SEL_SHIFT),
MMC_CLK_DIV_SHIFT = 0,
MMC_CLK_DIV_MASK = GENMASK(6, 0),

diff --git a/drivers/clk/rockchip/clk_rk3368.c b/drivers/clk/rockchip/clk_rk3368.c
index 33d2946..1327116 100644
--- a/drivers/clk/rockchip/clk_rk3368.c
+++ b/drivers/clk/rockchip/clk_rk3368.c
@@ -59,6 +59,8 @@ static const struct pll_div cpll_init_cfg = PLL_DIVISORS(CPLL_HZ, 1, 6);
#endif
#endif

+static ulong rk3368_clk_get_rate(struct clk *clk);
+
/* Get pll rate by id */
static uint32_t rkclk_pll_get_rate(struct rk3368_cru *cru,
enum rk3368_pll_id pll_id)
@@ -155,16 +157,17 @@ static void rkclk_init(struct rk3368_cru *cru)
}
#endif

+#if !IS_ENABLED(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(MMC_SUPPORT)
static ulong rk3368_mmc_get_clk(struct rk3368_cru *cru, uint clk_id)
{
u32 div, con, con_id, rate;
u32 pll_rate;

switch (clk_id) {
- case SCLK_SDMMC:
+ case HCLK_SDMMC:
con_id = 50;
break;
- case SCLK_EMMC:
+ case HCLK_EMMC:
con_id = 51;
break;
case SCLK_SDIO0:
@@ -175,7 +178,7 @@ static ulong rk3368_mmc_get_clk(struct rk3368_cru *cru, uint clk_id)
}

con = readl(&cru->clksel_con[con_id]);
- switch ((con & MMC_PLL_SEL_MASK) >> MMC_PLL_SEL_SHIFT) {
+ switch (con & MMC_PLL_SEL_MASK) {
case MMC_PLL_SEL_GPLL:
pll_rate = rkclk_pll_get_rate(cru, GPLL);
break;
@@ -183,6 +186,8 @@ static ulong rk3368_mmc_get_clk(struct rk3368_cru *cru, uint clk_id)
pll_rate = OSC_HZ;
break;
case MMC_PLL_SEL_CPLL:
+ pll_rate = rkclk_pll_get_rate(cru, CPLL);
+ break;
case MMC_PLL_SEL_USBPHY_480M:
default:
return -EINVAL;
@@ -190,23 +195,76 @@ static ulong rk3368_mmc_get_clk(struct rk3368_cru *cru, uint clk_id)
div = (con & MMC_CLK_DIV_MASK) >> MMC_CLK_DIV_SHIFT;
rate = DIV_TO_RATE(pll_rate, div);

+ debug("%s: raw rate %d (post-divide by 2)\n", __func__, rate);
return rate >> 1;
}

-static ulong rk3368_mmc_set_clk(struct rk3368_cru *cru,
- ulong clk_id, ulong rate)
+static ulong rk3368_mmc_find_best_rate_and_parent(struct clk *clk,
+ ulong rate,
+ u32 *best_mux,
+ u32 *best_div)
+{
+ int i;
+ ulong best_rate = 0;
+ const ulong MHz = 1000000;
+ const struct {
+ u32 mux;
+ ulong rate;
+ } parents[] = {
+ { .mux = MMC_PLL_SEL_CPLL, .rate = CPLL_HZ },
+ { .mux = MMC_PLL_SEL_GPLL, .rate = GPLL_HZ },
+ { .mux = MMC_PLL_SEL_24M, .rate = 24 * MHz }
+ };
+
+ debug("%s: target rate %ld\n", __func__, rate);
+ for (i = 0; i < ARRAY_SIZE(parents); ++i) {
+ /*
+ * Find the largest rate no larger than the target-rate for
+ * the current parent.
+ */
+ ulong parent_rate = parents[i].rate;
+ u32 div = DIV_ROUND_UP(parent_rate, rate);
+ u32 adj_div = div;
+ ulong new_rate = parent_rate / adj_div;
+
+ debug("%s: rate %ld, parent-mux %d, parent-rate %ld, div %d\n",
+ __func__, rate, parents[i].mux, parents[i].rate, div);
+
+ /* Skip, if not representable */
+ if ((div - 1) > MMC_CLK_DIV_MASK)
+ continue;
+
+ /* Skip, if we already have a better (or equal) solution */
+ if (new_rate <= best_rate)
+ continue;
+
+ /* This is our new best rate. */
+ best_rate = new_rate;
+ *best_mux = parents[i].mux;
+ *best_div = div - 1;
+ }
+
+ debug("%s: best_mux = %x, best_div = %d, best_rate = %ld\n",
+ __func__, *best_mux, *best_div, best_rate);
+
+ return best_rate;
+}
+
+static ulong rk3368_mmc_set_clk(struct clk *clk, ulong rate)
{
- u32 div;
- u32 con_id;
- u32 gpll_rate = rkclk_pll_get_rate(cru, GPLL);
+ struct rk3368_clk_priv *priv = dev_get_priv(clk->dev);
+ struct rk3368_cru *cru = priv->cru;
+ ulong clk_id = clk->id;
+ u32 con_id, mux = 0, div = 0;

- div = RATE_TO_DIV(gpll_rate, rate << 1);
+ /* Find the best parent and rate */
+ rk3368_mmc_find_best_rate_and_parent(clk, rate << 1, &mux, &div);

switch (clk_id) {
- case SCLK_SDMMC:
+ case HCLK_SDMMC:
con_id = 50;
break;
- case SCLK_EMMC:
+ case HCLK_EMMC:
con_id = 51;
break;
case SCLK_SDIO0:
@@ -216,33 +274,33 @@ static ulong rk3368_mmc_set_clk(struct rk3368_cru *cru,
return -EINVAL;
}

- if (div > 0x3f) {
- div = RATE_TO_DIV(OSC_HZ, rate);
- rk_clrsetreg(&cru->clksel_con[con_id],
- MMC_PLL_SEL_MASK | MMC_CLK_DIV_MASK,
- (MMC_PLL_SEL_24M << MMC_PLL_SEL_SHIFT) |
- (div << MMC_CLK_DIV_SHIFT));
- } else {
- rk_clrsetreg(&cru->clksel_con[con_id],
- MMC_PLL_SEL_MASK | MMC_CLK_DIV_MASK,
- (MMC_PLL_SEL_GPLL << MMC_PLL_SEL_SHIFT) |
- div << MMC_CLK_DIV_SHIFT);
- }
+ rk_clrsetreg(&cru->clksel_con[con_id],
+ MMC_PLL_SEL_MASK | MMC_CLK_DIV_MASK,
+ mux | div);

return rk3368_mmc_get_clk(cru, clk_id);
}
+#endif

static ulong rk3368_clk_get_rate(struct clk *clk)
{
struct rk3368_clk_priv *priv = dev_get_priv(clk->dev);
ulong rate = 0;

- debug("%s id:%ld\n", __func__, clk->id);
+ debug("%s: id %ld\n", __func__, clk->id);
switch (clk->id) {
+ case PLL_CPLL:
+ rate = rkclk_pll_get_rate(priv->cru, CPLL);
+ break;
+ case PLL_GPLL:
+ rate = rkclk_pll_get_rate(priv->cru, GPLL);
+ break;
+#if !IS_ENABLED(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(MMC_SUPPORT)
case HCLK_SDMMC:
case HCLK_EMMC:
rate = rk3368_mmc_get_clk(priv->cru, clk->id);
break;
+#endif
default:
return -ENOENT;
}
@@ -291,10 +349,15 @@ static ulong rk3368_clk_set_rate(struct clk *clk, ulong rate)
case CLK_DDR:
ret = rk3368_ddr_set_clk(priv->cru, rate);
break;
-
- case SCLK_SDMMC:
- case SCLK_EMMC:
- ret = rk3368_mmc_set_clk(priv->cru, clk->id, rate);
+#if !IS_ENABLED(CONFIG_SPL_BUILD) || CONFIG_IS_ENABLED(MMC_SUPPORT)
+ case HCLK_SDMMC:
+ case HCLK_EMMC:
+ ret = rk3368_mmc_set_clk(clk, rate);
+ break;
+#endif
+ case SCLK_MAC:
+ /* nothing to do, as this is an external clock */
+ ret = rate;
break;
default:
return -ENOENT;
--
2.1.4