Re: [PATCH v11 08/11] clk: realtek: Add support for MMC-tuned PLL clocks

[Brian Masney]

Hi Yu-Chun,

On Tue, Jul 28, 2026 at 10:28:03PM +0800, Yu-Chun Lin wrote:
> From: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> 
> Add clk_pll_mmc_ops for enable/disable, prepare, rate control, and status
> operations on MMC PLL clocks.
> 
> Also add clk_pll_mmc_phase_ops to support phase get/set operations.
> 
> Signed-off-by: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> Co-developed-by: Jyan Chou <jyanchou@xxxxxxxxxxx>
> Signed-off-by: Jyan Chou <jyanchou@xxxxxxxxxxx>
> Co-developed-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> Signed-off-by: Yu-Chun Lin <eleanor.lin@xxxxxxxxxxx>
> ---
> Changes in v11:
> - Remove PLL MMC MAINTAINER entry.
> - Add 'rtk_' prefix into struct names and function names.
> ---
>  drivers/clk/realtek/Kconfig       |   3 +
>  drivers/clk/realtek/Makefile      |   2 +
>  drivers/clk/realtek/clk-pll-mmc.c | 434 ++++++++++++++++++++++++++++++
>  drivers/clk/realtek/clk-pll.h     |  13 +
>  4 files changed, 452 insertions(+)
>  create mode 100644 drivers/clk/realtek/clk-pll-mmc.c
> 
> diff --git a/drivers/clk/realtek/Kconfig b/drivers/clk/realtek/Kconfig
> index ed97531e321d..2ff780581ae0 100644
> --- a/drivers/clk/realtek/Kconfig
> +++ b/drivers/clk/realtek/Kconfig
> @@ -27,4 +27,7 @@ config RTK_CLK_COMMON
>  	  multiple Realtek clock implementations, and include integration
>  	  with reset controllers where required.
>  
> +config RTK_CLK_PLL_MMC
> +	bool
> +
>  endif
> diff --git a/drivers/clk/realtek/Makefile b/drivers/clk/realtek/Makefile
> index 3b014240a211..97447e92bc35 100644
> --- a/drivers/clk/realtek/Makefile
> +++ b/drivers/clk/realtek/Makefile
> @@ -6,3 +6,5 @@ clk-rtk-y += clk-pll.o
>  clk-rtk-y += freq_table.o
>  clk-rtk-y += clk-regmap-gate.o
>  clk-rtk-y += clk-regmap-mux.o
> +
> +clk-rtk-$(CONFIG_RTK_CLK_PLL_MMC) += clk-pll-mmc.o
> diff --git a/drivers/clk/realtek/clk-pll-mmc.c b/drivers/clk/realtek/clk-pll-mmc.c
> new file mode 100644
> index 000000000000..8da1933a5a07
> --- /dev/null
> +++ b/drivers/clk/realtek/clk-pll-mmc.c
> @@ -0,0 +1,434 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +/*
> + * Copyright (C) 2021-2026 Realtek Semiconductor Corporation
> + * Author: Cheng-Yu Lee <cylee12@xxxxxxxxxxx>
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/export.h>
> +#include <linux/math64.h>
> +#include <linux/minmax.h>
> +#include <linux/module.h>
> +#include <linux/regmap.h>
> +#include "clk-pll.h"
> +
> +#define RTK_PLL_MMC_VAL_MIN 1
> +#define RTK_PLL_MMC_VAL_MAX 255
> +
> +#define RTK_PLL_EMMC1_OFFSET           0x0
> +#define RTK_PLL_EMMC2_OFFSET           0x4
> +#define RTK_PLL_EMMC3_OFFSET           0x8
> +#define RTK_PLL_EMMC4_OFFSET           0xc
> +#define RTK_PLL_SSC_DIG_EMMC1_OFFSET   0x0
> +#define RTK_PLL_SSC_DIG_EMMC3_OFFSET   0xc
> +#define RTK_PLL_SSC_DIG_EMMC4_OFFSET   0x10
> +
> +#define RTK_PLL_MMC_SSC_DIV_N_VAL      0x1b
> +
> +#define RTK_PLL_PHRT0_MASK             BIT(0)
> +#define RTK_PLL_PHSEL_MASK             GENMASK(4, 0)
> +#define RTK_PLL_SSCPLL_RS_MASK         GENMASK(12, 10)
> +#define RTK_PLL_SSCPLL_ICP_MASK        GENMASK(9, 5)
> +#define RTK_PLL_SSC_DIV_EXT_F_MASK     GENMASK(25, 13)
> +#define RTK_PLL_PI_IBSELH_MASK         GENMASK(28, 27)
> +#define RTK_PLL_SSC_DIV_N_MASK         GENMASK(23, 16)
> +#define RTK_PLL_NCODE_SSC_EMMC_MASK    GENMASK(20, 13)
> +#define RTK_PLL_FCODE_SSC_EMMC_MASK    GENMASK(12, 0)
> +#define RTK_PLL_GRAN_EST_EM_MC_MASK    GENMASK(20, 0)
> +#define RTK_PLL_EN_SSC_EMMC_MASK       BIT(0)
> +#define RTK_PLL_FLAG_INITAL_EMMC_MASK  BIT(8)
> +
> +#define RTK_PLL_PHRT0_SHIFT            1
> +#define RTK_PLL_SSCPLL_RS_SHIFT        10
> +#define RTK_PLL_SSCPLL_ICP_SHIFT       5
> +#define RTK_PLL_SSC_DIV_EXT_F_SHIFT    13
> +#define RTK_PLL_PI_IBSELH_SHIFT        27
> +#define RTK_PLL_SSC_DIV_N_SHIFT        16
> +#define RTK_PLL_NCODE_SSC_EMMC_SHIFT   13
> +#define RTK_PLL_FLAG_INITAL_EMMC_SHIFT 8
> +
> +#define CYCLE_DEGREES                  360
> +#define PHASE_STEPS                    32
> +#define PHASE_SCALE_FACTOR             1125
> +
> +static inline struct rtk_clk_regmap_pll_mmc *to_clk_pll_mmc(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap *clkr = to_rtk_clk_regmap(hw);
> +
> +	return container_of(clkr, struct rtk_clk_regmap_pll_mmc, clkr);
> +}
> +
> +static inline int get_phrt0(struct rtk_clk_regmap_pll_mmc *clkm, u32 *val)
> +{
> +	u32 reg;
> +	int ret;
> +
> +	ret = regmap_read(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC1_OFFSET, &reg);
> +	if (ret)
> +		return ret;
> +
> +	*val = (reg >> RTK_PLL_PHRT0_SHIFT) & RTK_PLL_PHRT0_MASK;
> +
> +	return 0;
> +}
> +
> +static inline int set_phrt0(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC1_OFFSET,
> +				  RTK_PLL_PHRT0_MASK << RTK_PLL_PHRT0_SHIFT,
> +				  val << RTK_PLL_PHRT0_SHIFT);
> +}
> +
> +static inline int get_phsel(struct rtk_clk_regmap_pll_mmc *clkm, int id, u32 *val)
> +{
> +	u32 sft = id ? 8 : 3;
> +	u32 raw_val;
> +	int ret;
> +
> +	ret = regmap_read(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC1_OFFSET, &raw_val);
> +	if (ret)
> +		return ret;
> +
> +	*val = (raw_val >> sft) & RTK_PLL_PHSEL_MASK;
> +
> +	return 0;
> +}
> +
> +static inline int set_phsel(struct rtk_clk_regmap_pll_mmc *clkm, int id, u32 val)
> +{
> +	u32 sft = id ? 8 : 3;
> +
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC1_OFFSET,
> +				  RTK_PLL_PHSEL_MASK << sft, val << sft);
> +}
> +
> +static inline int set_sscpll_rs(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC2_OFFSET,
> +				  RTK_PLL_SSCPLL_RS_MASK, val << RTK_PLL_SSCPLL_RS_SHIFT);
> +}
> +
> +static inline int set_sscpll_icp(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC2_OFFSET,
> +				  RTK_PLL_SSCPLL_ICP_MASK, val << RTK_PLL_SSCPLL_ICP_SHIFT);
> +}
> +
> +static inline int get_ssc_div_ext_f(struct rtk_clk_regmap_pll_mmc *clkm, u32 *val)
> +{
> +	u32 raw_val;
> +	int ret;
> +
> +	ret = regmap_read(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC2_OFFSET, &raw_val);
> +	if (ret)
> +		return ret;
> +
> +	*val = (raw_val & RTK_PLL_SSC_DIV_EXT_F_MASK) >> RTK_PLL_SSC_DIV_EXT_F_SHIFT;
> +
> +	return 0;
> +}
> +
> +static inline int set_ssc_div_ext_f(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC2_OFFSET,
> +				  RTK_PLL_SSC_DIV_EXT_F_MASK,
> +				  val << RTK_PLL_SSC_DIV_EXT_F_SHIFT);
> +}
> +
> +static inline int set_pi_ibselh(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC2_OFFSET,
> +				  RTK_PLL_PI_IBSELH_MASK, val << RTK_PLL_PI_IBSELH_SHIFT);
> +}
> +
> +static inline int set_ssc_div_n(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_update_bits(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC3_OFFSET,
> +				  RTK_PLL_SSC_DIV_N_MASK, val << RTK_PLL_SSC_DIV_N_SHIFT);
> +}
> +
> +static inline int get_ssc_div_n(struct rtk_clk_regmap_pll_mmc *clkm, u32 *val)
> +{
> +	int ret;
> +	u32 raw_val;
> +
> +	ret = regmap_read(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC3_OFFSET, &raw_val);
> +	if (ret)
> +		return ret;
> +
> +	*val = (raw_val & RTK_PLL_SSC_DIV_N_MASK) >> RTK_PLL_SSC_DIV_N_SHIFT;
> +
> +	return 0;
> +}
> +
> +static inline int set_pow_ctl(struct rtk_clk_regmap_pll_mmc *clkm, u32 val)
> +{
> +	return regmap_write(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC4_OFFSET, val);
> +}
> +
> +static inline int get_pow_ctl(struct rtk_clk_regmap_pll_mmc *clkm, u32 *val)
> +{
> +	int ret;
> +	u32 raw_val;
> +
> +	ret = regmap_read(clkm->clkr.regmap, clkm->pll_ofs + RTK_PLL_EMMC4_OFFSET, &raw_val);
> +	if (ret)
> +		return ret;
> +
> +	*val = raw_val;
> +
> +	return 0;
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_phase_set_phase(struct clk_hw *hw, int degrees)
> +{
> +	struct clk_hw *hwp = clk_hw_get_parent(hw);
> +	struct rtk_clk_regmap_pll_mmc *clkm;
> +	int phase_id;
> +	int ret;
> +	u32 val;
> +
> +	if (!hwp)
> +		return -ENOENT;
> +
> +	clkm = to_clk_pll_mmc(hwp);
> +	phase_id = (hw == &clkm->phase0_hw) ? 0 : 1;
> +	val = DIV_ROUND_CLOSEST(degrees * 100, PHASE_SCALE_FACTOR);
> +	ret = set_phsel(clkm, phase_id, val);
> +	if (ret)
> +		return ret;
> +
> +	usleep_range(10, 20);
> +
> +	return 0;
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_phase_get_phase(struct clk_hw *hw)
> +{
> +	struct clk_hw *hwp;
> +	struct rtk_clk_regmap_pll_mmc *clkm;
> +	int phase_id;
> +	int ret;
> +	u32 val;

Put in reverse Christmas tree order. You can combine the two int rows.

> +
> +	hwp = clk_hw_get_parent(hw);
> +	if (!hwp)
> +		return -ENOENT;
> +
> +	clkm = to_clk_pll_mmc(hwp);
> +	phase_id = (hw == &clkm->phase0_hw) ? 0 : 1;
> +	ret = get_phsel(clkm, phase_id, &val);
> +	if (ret)
> +		return ret;
> +
> +	val = DIV_ROUND_CLOSEST(val * CYCLE_DEGREES, PHASE_STEPS);
> +
> +	return val;
> +}
> +
> +const struct clk_ops rtk_clk_pll_mmc_phase_ops = {
> +	.set_phase = rtk_clk_regmap_pll_mmc_phase_set_phase,
> +	.get_phase = rtk_clk_regmap_pll_mmc_phase_get_phase,
> +};
> +EXPORT_SYMBOL_NS_GPL(rtk_clk_pll_mmc_phase_ops, "REALTEK_CLK");

Just looking at existing clk drivers, there's 5 that use
EXPORT_SYMBOL_NS_GPL(). 3 of them use CLK_FOO, so let's just make this
CLK_REALTEK for consistency with the other drivers. I like this because
it's framework/clk subsystem. I'm not going to call this out on the
other patches.

> +
> +static int rtk_clk_regmap_pll_mmc_prepare(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +
> +	return set_pow_ctl(clkm, 7);
> +}
> +
> +static void rtk_clk_regmap_pll_mmc_unprepare(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +
> +	set_pow_ctl(clkm, 0);
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_is_prepared(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +	u32 val;
> +	int ret;
> +
> +	ret = get_pow_ctl(clkm, &val);
> +	if (ret)
> +		return 1;
> +
> +	return val != 0x0;
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_enable(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +	int ret;
> +
> +	ret = set_phrt0(clkm, 1);
> +	if (ret)
> +		return ret;
> +
> +	udelay(10);
> +
> +	return 0;
> +}
> +
> +static void rtk_clk_regmap_pll_mmc_disable(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +
> +	set_phrt0(clkm, 0);
> +	udelay(10);
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_is_enabled(struct clk_hw *hw)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +	u32 val;
> +	int ret;
> +
> +	ret = get_phrt0(clkm, &val);
> +	if (ret)
> +		return 1;
> +
> +	return val == 0x1;
> +}
> +
> +static unsigned long rtk_clk_regmap_pll_mmc_recalc_rate(struct clk_hw *hw,
> +							unsigned long parent_rate)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +	u32 val, ext_f;
> +	u64 rate, base;
> +	int ret;
> +
> +	ret = get_ssc_div_n(clkm, &val);
> +	if (ret)
> +		return 0;
> +
> +	ret = get_ssc_div_ext_f(clkm, &ext_f);
> +	if (ret)
> +		return 0;
> +
> +	base = parent_rate / 4;
> +	rate = base * (val + 2);
> +	rate += div_u64(base * ext_f, 8192);
> +
> +	return rate;
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_determine_rate(struct clk_hw *hw, struct clk_rate_request *req)
> +{
> +	u32 val;
> +
> +	if (!req->best_parent_rate)
> +		return -EINVAL;
> +
> +	val = DIV_ROUND_CLOSEST_ULL((u64)req->rate * 4, req->best_parent_rate);
> +	val = clamp_t(u32, val, RTK_PLL_MMC_VAL_MIN, RTK_PLL_MMC_VAL_MAX);
> +	req->rate = req->best_parent_rate * val / 4;
> +
> +	return 0;
> +}
> +
> +static int rtk_clk_regmap_pll_mmc_set_rate(struct clk_hw *hw, unsigned long rate,
> +					   unsigned long parent_rate)
> +{
> +	struct rtk_clk_regmap_pll_mmc *clkm = to_clk_pll_mmc(hw);
> +	u32 val = RTK_PLL_MMC_SSC_DIV_N_VAL;
> +	int ret;
> +
> +	/*
> +	 * The 'rate' and 'parent_rate' are intentionally unused here.
> +	 *
> +	 * Despite receiving various rate requests (e.g., 26MHz, 52MHz, 200MHz),
> +	 * this function consistently configures the hardware for 27MHz (0x1b).
> +	 * This is because these settings reflect the input reference clock
> +	 * frequency to the SSCPLL, not the final PLL output frequency.
> +	 *
> +	 * The actual frequency division to achieve the requested eMMC rate
> +	 * is handled internally by the downstream eMMC host controller.
> +	 */
> +
> +	ret = regmap_update_bits(clkm->clkr.regmap,
> +				 clkm->ssc_dig_ofs + RTK_PLL_SSC_DIG_EMMC1_OFFSET,
> +				 RTK_PLL_FLAG_INITAL_EMMC_MASK,
> +				 0x0 << RTK_PLL_FLAG_INITAL_EMMC_SHIFT);

determine_rate() above implies that this PLL can do multiple frequencies.
There will be a mismatch between what the clk core thinks the frequency
is compared to what's actually programmed in the hardware. Should
determine_rate above also return the fixed rate as well?

Brian