[PATCH v18 04/12] mmc: renesas_sdhi: Add max_divider field to support SoC-specific clock divider ranges
From: Biju
Date: Mon Jun 22 2026 - 11:57:57 EST
From: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
The RZ/G3L SoC supports a maximum clock divider beyond the existing
hardcoded value of 512, requiring a configurable max_divider field.
Introduce max_divider in both renesas_sdhi_of_data and tmio_mmc_data.
Replace the two hardcoded 512 constants in renesas_sdhi_clk_enable()
and renesas_sdhi_set_clock() with host->pdata->max_divider. A fallback
of 512 is applied at probe time when no value is provided, preserving
behaviour for existing platforms.
All existing of_data entries across both the internal and system DMAC
drivers are updated to explicitly set max_divider = 512, consistent
with the approach taken for clk_mask in the previous patch.
Signed-off-by: Biju Das <biju.das.jz@xxxxxxxxxxxxxx>
---
v18:
* New patch.
---
drivers/mmc/host/renesas_sdhi.h | 2 ++
drivers/mmc/host/renesas_sdhi_core.c | 8 ++++++--
drivers/mmc/host/renesas_sdhi_internal_dmac.c | 3 +++
drivers/mmc/host/renesas_sdhi_sys_dmac.c | 4 ++++
include/linux/platform_data/tmio.h | 1 +
5 files changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h
index f926a36f213c..438b2a7afe76 100644
--- a/drivers/mmc/host/renesas_sdhi.h
+++ b/drivers/mmc/host/renesas_sdhi.h
@@ -23,6 +23,7 @@ struct renesas_sdhi_scc {
#define SDHI_FLAG_NEED_CLKH_FALLBACK BIT(0)
#define SDHI_CLK_MASK_DEFAULT 0x80000080
+#define SDHI_MAX_DIVIDER_DEFAULT 512
struct renesas_sdhi_of_data {
unsigned long tmio_flags;
@@ -39,6 +40,7 @@ struct renesas_sdhi_of_data {
unsigned short max_segs;
unsigned long sdhi_flags;
u64 clk_mask;
+ unsigned int max_divider;
};
#define SDHI_CALIB_TABLE_MAX 32
diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index cccc8fc235d2..7e48e78cbfab 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -117,7 +117,7 @@ static int renesas_sdhi_clk_enable(struct tmio_mmc_host *host)
* Minimum frequency is the minimum input clock frequency
* divided by our maximum divider.
*/
- mmc->f_min = max(clk_round_rate(priv->clk, 1) / 512, 1L);
+ mmc->f_min = max(clk_round_rate(priv->clk, 1) / host->pdata->max_divider, 1L);
/* enable 16bit data access on SDBUF as default */
renesas_sdhi_sdbuf_width(host, 16);
@@ -205,7 +205,7 @@ static void renesas_sdhi_set_clock(struct tmio_mmc_host *host,
}
host->mmc->actual_clock = renesas_sdhi_clk_update(host, new_clock);
- clock = host->mmc->actual_clock / 512;
+ clock = host->mmc->actual_clock / host->pdata->max_divider;
/*
* Add a margin of 1/1024 rate higher to the clock rate in order
@@ -1137,6 +1137,7 @@ int renesas_sdhi_probe(struct platform_device *pdev,
mmc_data->max_blk_count = of_data->max_blk_count;
mmc_data->max_segs = of_data->max_segs;
mmc_data->clk_mask = of_data->clk_mask;
+ mmc_data->max_divider = of_data->max_divider;
dma_priv->dma_buswidth = of_data->dma_buswidth;
host->bus_shift = of_data->bus_shift;
/* Fallback for old DTs */
@@ -1148,6 +1149,9 @@ int renesas_sdhi_probe(struct platform_device *pdev,
if (!mmc_data->clk_mask)
mmc_data->clk_mask = SDHI_CLK_MASK_DEFAULT;
+ if (!mmc_data->max_divider)
+ mmc_data->max_divider = SDHI_MAX_DIVIDER_DEFAULT;
+
host->write16_hook = renesas_sdhi_write16_hook;
host->clk_enable = renesas_sdhi_clk_enable;
host->clk_disable = renesas_sdhi_clk_disable;
diff --git a/drivers/mmc/host/renesas_sdhi_internal_dmac.c b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
index 2865ec30be66..c91b910488da 100644
--- a/drivers/mmc/host/renesas_sdhi_internal_dmac.c
+++ b/drivers/mmc/host/renesas_sdhi_internal_dmac.c
@@ -103,6 +103,7 @@ static const struct renesas_sdhi_of_data of_data_rza2 = {
.max_blk_count = UINT_MAX / TMIO_MAX_BLK_SIZE,
.max_segs = 1,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const struct renesas_sdhi_of_data of_data_rcar_gen3 = {
@@ -121,6 +122,7 @@ static const struct renesas_sdhi_of_data of_data_rcar_gen3 = {
.max_segs = 1,
.sdhi_flags = SDHI_FLAG_NEED_CLKH_FALLBACK,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const struct renesas_sdhi_of_data of_data_rcar_gen3_no_sdh_fallback = {
@@ -138,6 +140,7 @@ static const struct renesas_sdhi_of_data of_data_rcar_gen3_no_sdh_fallback = {
.max_blk_count = UINT_MAX / TMIO_MAX_BLK_SIZE,
.max_segs = 1,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const u8 r8a7796_es13_calib_table[2][SDHI_CALIB_TABLE_MAX] = {
diff --git a/drivers/mmc/host/renesas_sdhi_sys_dmac.c b/drivers/mmc/host/renesas_sdhi_sys_dmac.c
index d1a4f65ddd91..d91b48dce8c9 100644
--- a/drivers/mmc/host/renesas_sdhi_sys_dmac.c
+++ b/drivers/mmc/host/renesas_sdhi_sys_dmac.c
@@ -30,6 +30,7 @@
static const struct renesas_sdhi_of_data of_default_cfg = {
.tmio_flags = TMIO_MMC_HAS_IDLE_WAIT,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const struct renesas_sdhi_of_data of_rz_compatible = {
@@ -39,6 +40,7 @@ static const struct renesas_sdhi_of_data of_rz_compatible = {
.capabilities = MMC_CAP_SD_HIGHSPEED | MMC_CAP_SDIO_IRQ |
MMC_CAP_WAIT_WHILE_BUSY,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const struct renesas_sdhi_of_data of_rcar_gen1_compatible = {
@@ -47,6 +49,7 @@ static const struct renesas_sdhi_of_data of_rcar_gen1_compatible = {
MMC_CAP_WAIT_WHILE_BUSY,
.capabilities2 = MMC_CAP2_NO_WRITE_PROTECT,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
/* Definitions for sampling clocks */
@@ -75,6 +78,7 @@ static const struct renesas_sdhi_of_data of_rcar_gen2_compatible = {
.taps_num = ARRAY_SIZE(rcar_gen2_scc_taps),
.max_blk_count = UINT_MAX / TMIO_MAX_BLK_SIZE,
.clk_mask = SDHI_CLK_MASK_DEFAULT,
+ .max_divider = SDHI_MAX_DIVIDER_DEFAULT,
};
static const struct of_device_id renesas_sdhi_sys_dmac_of_match[] = {
diff --git a/include/linux/platform_data/tmio.h b/include/linux/platform_data/tmio.h
index 76056d49f5e0..27ea21c00419 100644
--- a/include/linux/platform_data/tmio.h
+++ b/include/linux/platform_data/tmio.h
@@ -62,5 +62,6 @@ struct tmio_mmc_data {
unsigned int max_blk_count;
unsigned short max_segs;
u64 clk_mask;
+ unsigned int max_divider;
};
#endif
--
2.43.0