[PATCH 3/3] mmc: dw_mmc-rockchip: Add internal phase support

Detlev Casanova
2024-08-02T15:37:12Z

From: Shawn Lin <shawn.lin@rock-chips.com>

Some Rockchip devices put the phase settings into the dw_mmc controller.

The feature is implemented in devices where the USRID register contains
0x20230002.

Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com>
Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
---
drivers/mmc/host/dw_mmc-rockchip.c | 180 +++++++++++++++++++++++++++--
1 file changed, 169 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc-rockchip.c b/drivers/mmc/host/dw_mmc-rockchip.c
index c47b93d99a1b3..2f474e7eb21dc 100644
--- a/drivers/mmc/host/dw_mmc-rockchip.c
+++ b/drivers/mmc/host/dw_mmc-rockchip.c
@@ -16,6 +16,17 @@
#include "dw_mmc-pltfm.h"

#define RK3288_CLKGEN_DIV 2
+#define USRID_INTER_PHASE 0x20230001
+#define SDMMC_TIMING_CON0 0x130
+#define SDMMC_TIMING_CON1 0x134
+#define ROCKCHIP_MMC_DELAY_SEL BIT(10)
+#define ROCKCHIP_MMC_DEGREE_MASK 0x3
+#define ROCKCHIP_MMC_DELAYNUM_OFFSET 2
+#define ROCKCHIP_MMC_DELAYNUM_MASK (0xff << ROCKCHIP_MMC_DELAYNUM_OFFSET)
+#define PSECS_PER_SEC 1000000000000LL
+#define ROCKCHIP_MMC_DELAY_ELEMENT_PSEC 60
+#define HIWORD_UPDATE(val, mask, shift) \
+ ((val) << (shift) | (mask) << ((shift) + 16))

static const unsigned int freqs[] = { 100000, 200000, 300000, 400000 };

@@ -25,9 +36,121 @@ struct dw_mci_rockchip_priv_data {
int default_sample_phase;
int num_phases;
bool use_v2_tuning;
+ int usrid;
int last_degree;
};

+/*
+ * Each fine delay is between 44ps-77ps. Assume each fine delay is 60ps to
+ * simplify calculations. So 45degs could be anywhere between 33deg and 57.8deg.
+ */
+static int rockchip_mmc_get_phase(struct dw_mci *host, bool sample)
+{
+ unsigned long rate = clk_get_rate(host->ciu_clk);
+ u32 raw_value;
+ u16 degrees;
+ u32 delay_num = 0;
+
+ /* Constant signal, no measurable phase shift */
+ if (!rate)
+ return 0;
+
+ if (sample)
+ raw_value = mci_readl(host, TIMING_CON1) >> 1;
+ else
+ raw_value = mci_readl(host, TIMING_CON0) >> 1;
+
+ degrees = (raw_value & ROCKCHIP_MMC_DEGREE_MASK) * 90;
+
+ if (raw_value & ROCKCHIP_MMC_DELAY_SEL) {
+ /* degrees/delaynum * 1000000 */
+ unsigned long factor = (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10) *
+ 36 * (rate / 10000);
+
+ delay_num = (raw_value & ROCKCHIP_MMC_DELAYNUM_MASK);
+ delay_num >>= ROCKCHIP_MMC_DELAYNUM_OFFSET;
+ degrees += DIV_ROUND_CLOSEST(delay_num * factor, 1000000);
+ }
+
+ return degrees % 360;
+}
+
+static int rockchip_mmc_set_phase(struct dw_mci *host, bool sample, int degrees)
+{
+ unsigned long rate = clk_get_rate(host->ciu_clk);
+ u8 nineties, remainder;
+ u8 delay_num;
+ u32 raw_value;
+ u32 delay;
+
+ /*
+ * The below calculation is based on the output clock from
+ * MMC host to the card, which expects the phase clock inherits
+ * the clock rate from its parent, namely the output clock
+ * provider of MMC host. However, things may go wrong if
+ * (1) It is orphan.
+ * (2) It is assigned to the wrong parent.
+ *
+ * This check help debug the case (1), which seems to be the
+ * most likely problem we often face and which makes it difficult
+ * for people to debug unstable mmc tuning results.
+ */
+ if (!rate) {
+ dev_err(host->dev, "%s: invalid clk rate\n", __func__);
+ return -EINVAL;
+ }
+
+ nineties = degrees / 90;
+ remainder = (degrees % 90);
+
+ /*
+ * Due to the inexact nature of the "fine" delay, we might
+ * actually go non-monotonic. We don't go _too_ monotonic
+ * though, so we should be OK. Here are options of how we may
+ * work:
+ *
+ * Ideally we end up with:
+ * 1.0, 2.0, ..., 69.0, 70.0, ..., 89.0, 90.0
+ *
+ * On one extreme (if delay is actually 44ps):
+ * .73, 1.5, ..., 50.6, 51.3, ..., 65.3, 90.0
+ * The other (if delay is actually 77ps):
+ * 1.3, 2.6, ..., 88.6. 89.8, ..., 114.0, 90
+ *
+ * It's possible we might make a delay that is up to 25
+ * degrees off from what we think we're making. That's OK
+ * though because we should be REALLY far from any bad range.
+ */
+
+ /*
+ * Convert to delay; do a little extra work to make sure we
+ * don't overflow 32-bit / 64-bit numbers.
+ */
+ delay = 10000000; /* PSECS_PER_SEC / 10000 / 10 */
+ delay *= remainder;
+ delay = DIV_ROUND_CLOSEST(delay,
+ (rate / 1000) * 36 *
+ (ROCKCHIP_MMC_DELAY_ELEMENT_PSEC / 10));
+
+ delay_num = (u8) min_t(u32, delay, 255);
+
+ raw_value = delay_num ? ROCKCHIP_MMC_DELAY_SEL : 0;
+ raw_value |= delay_num << ROCKCHIP_MMC_DELAYNUM_OFFSET;
+ raw_value |= nineties;
+
+ if (sample)
+ mci_writel(host, TIMING_CON1, HIWORD_UPDATE(raw_value, 0x07ff, 1));
+ else
+ mci_writel(host, TIMING_CON0, HIWORD_UPDATE(raw_value, 0x07ff, 1));
+
+ dev_dbg(host->dev, "set %s_phase(%d) delay_nums=%u actual_degrees=%d\n",
+ sample ? "sample" : "drv", degrees, delay_num,
+ rockchip_mmc_get_phase(host, sample)
+ );
+
+ return 0;
+}
+
static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
{
struct dw_mci_rockchip_priv_data *priv = host->priv;
@@ -65,8 +188,12 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
}

/* Make sure we use phases which we can enumerate with */
- if (!IS_ERR(priv->sample_clk) && ios->timing <= MMC_TIMING_SD_HS)
- clk_set_phase(priv->sample_clk, priv->default_sample_phase);
+ if (!IS_ERR(priv->sample_clk) && ios->timing <= MMC_TIMING_SD_HS) {
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, true, priv->default_sample_phase);
+ else
+ clk_set_phase(priv->sample_clk, priv->default_sample_phase);
+ }

/*
* Set the drive phase offset based on speed mode to achieve hold times.
@@ -129,7 +256,10 @@ static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
break;
}

- clk_set_phase(priv->drv_clk, phase);
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, false, phase);
+ else
+ clk_set_phase(priv->drv_clk, phase);
}
}

@@ -147,7 +277,10 @@ static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)

if (inherit) {
inherit = false;
- i = clk_get_phase(priv->sample_clk) / 90 - 1;
+ if (priv->usrid == USRID_INTER_PHASE)
+ i = rockchip_mmc_get_phase(host, true) / 90;
+ else
+ i = clk_get_phase(priv->sample_clk) / 90 - 1;
goto done;
}

@@ -156,7 +289,12 @@ static int dw_mci_v2_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
if (degrees[i] == priv->last_degree)
continue;

- clk_set_phase(priv->sample_clk, degrees[i]);
+ u32 degree = degrees[i] + priv->last_degree + 90;
+ degree = degree % 360;
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, true, degree);
+ else
+ clk_set_phase(priv->sample_clk, degree);
if (!mmc_send_tuning(mmc, opcode, NULL))
break;
}
@@ -209,8 +347,15 @@ static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)

/* Try each phase and extract good ranges */
for (i = 0; i < priv->num_phases; ) {
- clk_set_phase(priv->sample_clk,
- TUNING_ITERATION_TO_PHASE(i, priv->num_phases));
+ /* Cannot guarantee any phases larger than 270 would work well */
+ if (TUNING_ITERATION_TO_PHASE(i, priv->num_phases) > 270)
+ break;
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, true,
+ TUNING_ITERATION_TO_PHASE(i, priv->num_phases));
+ else
+ clk_set_phase(priv->sample_clk,
+ TUNING_ITERATION_TO_PHASE(i, priv->num_phases));

v = !mmc_send_tuning(mmc, opcode, NULL);

@@ -256,7 +401,10 @@ static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
}

if (ranges[0].start == 0 && ranges[0].end == priv->num_phases - 1) {
- clk_set_phase(priv->sample_clk, priv->default_sample_phase);
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, true, priv->default_sample_phase);
+ else
+ clk_set_phase(priv->sample_clk, priv->default_sample_phase);
dev_info(host->dev, "All phases work, using default phase %d.",
priv->default_sample_phase);
goto free;
@@ -296,9 +444,12 @@ static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
dev_info(host->dev, "Successfully tuned phase to %d\n",
TUNING_ITERATION_TO_PHASE(middle_phase, priv->num_phases));

- clk_set_phase(priv->sample_clk,
- TUNING_ITERATION_TO_PHASE(middle_phase,
- priv->num_phases));
+ if (priv->usrid == USRID_INTER_PHASE)
+ rockchip_mmc_set_phase(host, true, TUNING_ITERATION_TO_PHASE(middle_phase,
+ priv->num_phases));
+ else
+ clk_set_phase(priv->sample_clk, TUNING_ITERATION_TO_PHASE(middle_phase,
+ priv->num_phases));

free:
kfree(ranges);
@@ -341,6 +492,7 @@ static int dw_mci_rk3288_parse_dt(struct dw_mci *host)
static int dw_mci_rockchip_init(struct dw_mci *host)
{
int ret, i;
+ struct dw_mci_rockchip_priv_data *priv = host->priv;

/* It is slot 8 on Rockchip SoCs */
host->sdio_id0 = 8;
@@ -364,6 +516,12 @@ static int dw_mci_rockchip_init(struct dw_mci *host)
dev_warn(host->dev, "no valid minimum freq: %d\n", ret);
}

+ priv->usrid = mci_readl(host, USRID);
+ if (priv->usrid == USRID_INTER_PHASE) {
+ priv->sample_clk = NULL;
+ priv->drv_clk = NULL;
+ }
+
return 0;
}

--
2.46.0