Hi Geert, Stephen,
> -----Original Message-----
> From: Prabhakar <prabhakar.cse...@gmail.com>
> Sent: 12 May 2025 19:43
> Subject: [PATCH v5 1/4] clk: renesas: rzv2h-cpg: Add support for DSI clocks
>
> From: Lad Prabhakar <prabhakar.mahadev-lad...@bp.renesas.com>
>
> Add support for PLLDSI and PLLDSI divider clocks.
>
> Introduce the `renesas-rzv2h-dsi.h` header to centralize and share
> PLLDSI-related data structures,
> limits, and algorithms between the RZ/V2H CPG and DSI drivers.
>
> The DSI PLL is functionally similar to the CPG's PLLDSI, but has slightly
> different parameter limits
> and omits the programmable divider present in CPG. To ensure precise
> frequency calculations-especially
> for milliHz-level accuracy needed by the DSI driver-the shared algorithm
> allows both drivers to
> compute PLL parameters consistently using the same logic and input clock.
>
> Co-developed-by: Fabrizio Castro <fabrizio.castro...@renesas.com>
> Signed-off-by: Fabrizio Castro <fabrizio.castro...@renesas.com>
> Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad...@bp.renesas.com>
> ---
> v4->v5:
> - No changes
>
> v3->v4:
> - Corrected parameter name in rzv2h_dsi_get_pll_parameters_values()
> description freq_millihz
>
> v2->v3:
> - Update the commit message to clarify the purpose of `renesas-rzv2h-dsi.h`
> header
> - Used mul_u32_u32() in rzv2h_cpg_plldsi_div_determine_rate()
> - Replaced *_mhz to *_millihz for clarity
> - Updated u64->u32 for fvco limits
> - Initialized the members in declaration order for
> RZV2H_CPG_PLL_DSI_LIMITS() macro
> - Used clk_div_mask() in rzv2h_cpg_plldsi_div_recalc_rate()
> - Replaced `unsigned long long` with u64
> - Dropped rzv2h_cpg_plldsi_clk_recalc_rate() and reused
> rzv2h_cpg_pll_clk_recalc_rate() instead
> - In rzv2h_cpg_plldsi_div_set_rate() followed the same style
> of RMW-operation as done in the other functions
> - Renamed rzv2h_cpg_plldsi_set_rate() to rzv2h_cpg_pll_set_rate()
> - Dropped rzv2h_cpg_plldsi_clk_register() and reused
> rzv2h_cpg_pll_clk_register() instead
> - Added a gaurd in renesas-rzv2h-dsi.h header
>
> v1->v2:
> - No changes
> ---
> drivers/clk/renesas/rzv2h-cpg.c | 237 +++++++++++++++++++++++++-
> drivers/clk/renesas/rzv2h-cpg.h | 14 ++
> include/linux/clk/renesas-rzv2h-dsi.h | 211 +++++++++++++++++++++++
> 3 files changed, 460 insertions(+), 2 deletions(-) create mode 100644
> include/linux/clk/renesas-
> rzv2h-dsi.h
>
> diff --git a/drivers/clk/renesas/rzv2h-cpg.c
> b/drivers/clk/renesas/rzv2h-cpg.c index
> 882e301c2d1b..ccf6a664e71d 100644
> --- a/drivers/clk/renesas/rzv2h-cpg.c
> +++ b/drivers/clk/renesas/rzv2h-cpg.c
> @@ -14,9 +14,13 @@
> #include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/clk-provider.h>
> +#include <linux/clk/renesas-rzv2h-dsi.h>
> #include <linux/delay.h>
> #include <linux/init.h>
> #include <linux/iopoll.h>
> +#include <linux/math.h>
> +#include <linux/math64.h>
> +#include <linux/minmax.h>
> #include <linux/mod_devicetable.h>
> #include <linux/module.h>
> #include <linux/of.h>
> @@ -26,6 +30,7 @@
> #include <linux/refcount.h>
> #include <linux/reset-controller.h>
> #include <linux/string_choices.h>
> +#include <linux/units.h>
>
> #include <dt-bindings/clock/renesas-cpg-mssr.h>
>
> @@ -48,6 +53,7 @@
> #define CPG_PLL_STBY(x) ((x))
> #define CPG_PLL_STBY_RESETB BIT(0)
> #define CPG_PLL_STBY_RESETB_WEN BIT(16)
> +#define CPG_PLL_STBY_SSCGEN_WEN BIT(18)
> #define CPG_PLL_CLK1(x) ((x) + 0x004)
> #define CPG_PLL_CLK1_KDIV(x) ((s16)FIELD_GET(GENMASK(31, 16), (x)))
> #define CPG_PLL_CLK1_MDIV(x) FIELD_GET(GENMASK(15, 6), (x))
> @@ -79,6 +85,8 @@
> * @last_dt_core_clk: ID of the last Core Clock exported to DT
> * @mstop_count: Array of mstop values
> * @rcdev: Reset controller entity
> + * @dsi_limits: PLL DSI parameters limits
> + * @plldsi_div_parameters: PLL DSI and divider parameters configuration
> */
> struct rzv2h_cpg_priv {
> struct device *dev;
> @@ -95,6 +103,9 @@ struct rzv2h_cpg_priv {
> atomic_t *mstop_count;
>
> struct reset_controller_dev rcdev;
> +
> + const struct rzv2h_pll_div_limits *dsi_limits;
> + struct rzv2h_plldsi_parameters plldsi_div_parameters;
> };
>
> #define rcdev_to_priv(x) container_of(x, struct rzv2h_cpg_priv, rcdev)
> @@ -150,6 +161,24 @@ struct ddiv_clk {
>
> #define to_ddiv_clock(_div) container_of(_div, struct ddiv_clk, div)
>
> +/**
> + * struct rzv2h_plldsi_div_clk - PLL DSI DDIV clock
> + *
> + * @dtable: divider table
> + * @priv: CPG private data
> + * @hw: divider clk
> + * @ddiv: divider configuration
> + */
> +struct rzv2h_plldsi_div_clk {
> + const struct clk_div_table *dtable;
> + struct rzv2h_cpg_priv *priv;
> + struct clk_hw hw;
> + struct ddiv ddiv;
> +};
> +
> +#define to_plldsi_div_clk(_hw) \
> + container_of(_hw, struct rzv2h_plldsi_div_clk, hw)
> +
> static int rzv2h_cpg_pll_clk_is_enabled(struct clk_hw *hw) {
> struct pll_clk *pll_clk = to_pll(hw);
> @@ -198,6 +227,188 @@ static int rzv2h_cpg_pll_clk_enable(struct clk_hw *hw)
> return ret;
> }
>
> +static unsigned long rzv2h_cpg_plldsi_div_recalc_rate(struct clk_hw *hw,
> + unsigned long parent_rate)
> +{
> + struct rzv2h_plldsi_div_clk *dsi_div = to_plldsi_div_clk(hw);
> + struct rzv2h_cpg_priv *priv = dsi_div->priv;
> + struct ddiv ddiv = dsi_div->ddiv;
> + u32 div;
> +
> + div = readl(priv->base + ddiv.offset);
> + div >>= ddiv.shift;
> + div &= clk_div_mask(ddiv.width);
> + div = dsi_div->dtable[div].div;
> +
> + return DIV_ROUND_CLOSEST_ULL(parent_rate, div); }
> +
> +static int rzv2h_cpg_plldsi_div_determine_rate(struct clk_hw *hw,
> + struct clk_rate_request *req) {
> + struct rzv2h_plldsi_div_clk *dsi_div = to_plldsi_div_clk(hw);
> + struct rzv2h_cpg_priv *priv = dsi_div->priv;
> + struct rzv2h_plldsi_parameters *dsi_dividers =
> &priv->plldsi_div_parameters;
> + u64 rate_millihz;
> +
> + /*
> + * Adjust the requested clock rate (`req->rate`) to ensure it falls
> within
> + * the supported range of 5.44 MHz to 187.5 MHz.
> + */
> + req->rate = clamp(req->rate, 5440000UL, 187500000UL);
> +
> + rate_millihz = mul_u32_u32(req->rate, MILLI);
> + if (rate_millihz == dsi_dividers->error_millihz +
> dsi_dividers->freq_millihz)
> + goto exit_determine_rate;
> +
> + if (!rzv2h_dsi_get_pll_parameters_values(priv->dsi_limits,
> + dsi_dividers, rate_millihz)) {
> + dev_err(priv->dev,
> + "failed to determine rate for req->rate: %lu\n",
> + req->rate);
> + return -EINVAL;
> + }
> +
> +exit_determine_rate:
> + req->best_parent_rate = req->rate * dsi_dividers->csdiv;
> +
> + return 0;
> +};
> +
> +static int rzv2h_cpg_plldsi_div_set_rate(struct clk_hw *hw,
> + unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct rzv2h_plldsi_div_clk *dsi_div = to_plldsi_div_clk(hw);
> + struct rzv2h_cpg_priv *priv = dsi_div->priv;
> + struct rzv2h_plldsi_parameters *dsi_dividers =
> &priv->plldsi_div_parameters;
> + struct ddiv ddiv = dsi_div->ddiv;
> + const struct clk_div_table *clkt;
> + bool div_found = false;
> + u32 val, shift, div;
> +
> + div = dsi_dividers->csdiv;
> + for (clkt = dsi_div->dtable; clkt->div; clkt++) {
> + if (clkt->div == div) {
> + div_found = true;
> + break;
> + }
> + }
> +
> + if (!div_found)
> + return -EINVAL;
> +
> + shift = ddiv.shift;
> + val = readl(priv->base + ddiv.offset) | DDIV_DIVCTL_WEN(shift);
> + val &= ~(clk_div_mask(ddiv.width) << shift);
> + val |= (u32)clkt->val << shift;
> + writel(val, priv->base + ddiv.offset);
> +
> + return 0;
> +};
> +
> +static const struct clk_ops rzv2h_cpg_plldsi_div_ops = {
> + .recalc_rate = rzv2h_cpg_plldsi_div_recalc_rate,
> + .determine_rate = rzv2h_cpg_plldsi_div_determine_rate,
> + .set_rate = rzv2h_cpg_plldsi_div_set_rate, };
> +
> +static struct clk * __init
> +rzv2h_cpg_plldsi_div_clk_register(const struct cpg_core_clk *core,
> + struct rzv2h_cpg_priv *priv)
> +{
> + struct rzv2h_plldsi_div_clk *clk_hw_data;
> + struct clk **clks = priv->clks;
> + struct clk_init_data init;
> + const struct clk *parent;
> + const char *parent_name;
> + struct clk_hw *clk_hw;
> + int ret;
> +
> + parent = clks[core->parent];
> + if (IS_ERR(parent))
> + return ERR_CAST(parent);
> +
> + clk_hw_data = devm_kzalloc(priv->dev, sizeof(*clk_hw_data), GFP_KERNEL);
> + if (!clk_hw_data)
> + return ERR_PTR(-ENOMEM);
> +
> + clk_hw_data->priv = priv;
> + clk_hw_data->ddiv = core->cfg.ddiv;
> + clk_hw_data->dtable = core->dtable;
> +
> + parent_name = __clk_get_name(parent);
> + init.name = core->name;
> + init.ops = &rzv2h_cpg_plldsi_div_ops;
> + init.flags = core->flag;
> + init.parent_names = &parent_name;
> + init.num_parents = 1;
> +
> + clk_hw = &clk_hw_data->hw;
> + clk_hw->init = &init;
> +
> + ret = devm_clk_hw_register(priv->dev, clk_hw);
> + if (ret)
> + return ERR_PTR(ret);
> +
> + return clk_hw->clk;
> +}
> +
> +static long rzv2h_cpg_plldsi_round_rate(struct clk_hw *hw,
> + unsigned long rate,
> + unsigned long *parent_rate)
> +{
> + return clamp(rate, 25000000UL, 375000000UL); }
> +
> +static int rzv2h_cpg_pll_set_rate(struct clk_hw *hw,
> + unsigned long rate,
> + unsigned long parent_rate)
> +{
> + struct pll_clk *pll_clk = to_pll(hw);
> + struct rzv2h_cpg_priv *priv = pll_clk->priv;
> + struct rzv2h_plldsi_parameters *dsi_dividers;
> + struct pll pll = pll_clk->pll;
> + u16 offset = pll.offset;
> + u32 val;
> + int ret;
> +
> + /* Put PLL into standby mode */
> + writel(CPG_PLL_STBY_RESETB_WEN, priv->base + CPG_PLL_STBY(offset));
> + ret = readl_poll_timeout_atomic(priv->base + CPG_PLL_MON(offset),
> + val, !(val & CPG_PLL_MON_LOCK),
> + 100, 2000);
> + if (ret) {
> + dev_err(priv->dev, "Failed to put PLLDSI into standby mode");
> + return ret;
> + }
> +
> + dsi_dividers = &priv->plldsi_div_parameters;
> + /* Output clock setting 1 */
> + writel((dsi_dividers->k << 16) | (dsi_dividers->m << 6) |
> (dsi_dividers->p),
> + priv->base + CPG_PLL_CLK1(offset));
> +
> + /* Output clock setting 2 */
> + val = readl(priv->base + CPG_PLL_CLK2(offset));
> + writel((val & ~GENMASK(2, 0)) | dsi_dividers->s,
> + priv->base + CPG_PLL_CLK2(offset));
> +
> + /* Put PLL to normal mode */
> + writel(CPG_PLL_STBY_RESETB_WEN | CPG_PLL_STBY_RESETB,
> + priv->base + CPG_PLL_STBY(offset));
> +
> + /* PLL normal mode transition, output clock stability check */
> + ret = readl_poll_timeout_atomic(priv->base + CPG_PLL_MON(offset),
> + val, (val & CPG_PLL_MON_LOCK),
> + 100, 2000);
> + if (ret) {
> + dev_err(priv->dev, "Failed to put PLLDSI into normal mode");
> + return ret;
> + }
> +
> + return 0;
> +};
> +
> static unsigned long rzv2h_cpg_pll_clk_recalc_rate(struct clk_hw *hw,
> unsigned long parent_rate)
> {
> @@ -219,6 +430,12 @@ static unsigned long
> rzv2h_cpg_pll_clk_recalc_rate(struct clk_hw *hw,
> return DIV_ROUND_CLOSEST_ULL(rate, CPG_PLL_CLK1_PDIV(clk1)); }
>
> +static const struct clk_ops rzv2h_cpg_plldsi_ops = {
> + .recalc_rate = rzv2h_cpg_pll_clk_recalc_rate,
> + .round_rate = rzv2h_cpg_plldsi_round_rate,
> + .set_rate = rzv2h_cpg_pll_set_rate,
> +};
> +
> static const struct clk_ops rzv2h_cpg_pll_ops = {
> .is_enabled = rzv2h_cpg_pll_clk_is_enabled,
> .enable = rzv2h_cpg_pll_clk_enable,
> @@ -228,7 +445,8 @@ static const struct clk_ops rzv2h_cpg_pll_ops = { static
> struct clk * __init
> rzv2h_cpg_pll_clk_register(const struct cpg_core_clk *core,
> struct rzv2h_cpg_priv *priv,
> - const struct clk_ops *ops)
> + const struct clk_ops *ops,
> + bool turn_on)
> {
> void __iomem *base = priv->base;
> struct device *dev = priv->dev;
> @@ -258,6 +476,13 @@ rzv2h_cpg_pll_clk_register(const struct cpg_core_clk
> *core,
> pll_clk->base = base;
> pll_clk->priv = priv;
>
> + if (turn_on) {
> + /* Disable SSC and turn on PLL clock when init */
> + writel(CPG_PLL_STBY_RESETB_WEN | CPG_PLL_STBY_RESETB |
> + CPG_PLL_STBY_SSCGEN_WEN,
> + base + CPG_PLL_STBY(pll_clk->pll.offset));
> + }
> +
> ret = devm_clk_hw_register(dev, &pll_clk->hw);
> if (ret)
> return ERR_PTR(ret);
> @@ -499,7 +724,7 @@ rzv2h_cpg_register_core_clk(const struct cpg_core_clk
> *core,
> clk = clk_hw->clk;
> break;
> case CLK_TYPE_PLL:
> - clk = rzv2h_cpg_pll_clk_register(core, priv,
> &rzv2h_cpg_pll_ops);
> + clk = rzv2h_cpg_pll_clk_register(core, priv, &rzv2h_cpg_pll_ops,
> +false);
> break;
> case CLK_TYPE_DDIV:
> clk = rzv2h_cpg_ddiv_clk_register(core, priv); @@ -507,6
> +732,12 @@
> rzv2h_cpg_register_core_clk(const struct cpg_core_clk *core,
> case CLK_TYPE_SMUX:
> clk = rzv2h_cpg_mux_clk_register(core, priv);
> break;
> + case CLK_TYPE_PLLDSI:
> + clk = rzv2h_cpg_pll_clk_register(core, priv,
> &rzv2h_cpg_plldsi_ops, true);
> + break;
> + case CLK_TYPE_PLLDSI_DIV:
> + clk = rzv2h_cpg_plldsi_div_clk_register(core, priv);
> + break;
> default:
> goto fail;
> }
> @@ -1043,6 +1274,8 @@ static int __init rzv2h_cpg_probe(struct
> platform_device *pdev)
> priv->last_dt_core_clk = info->last_dt_core_clk;
> priv->num_resets = info->num_resets;
>
> + priv->dsi_limits = info->plldsi_limits;
> +
> for (i = 0; i < nclks; i++)
> clks[i] = ERR_PTR(-ENOENT);
>
> diff --git a/drivers/clk/renesas/rzv2h-cpg.h
> b/drivers/clk/renesas/rzv2h-cpg.h index
> cd6bcd4f2901..6f662fa86ac4 100644
> --- a/drivers/clk/renesas/rzv2h-cpg.h
> +++ b/drivers/clk/renesas/rzv2h-cpg.h
> @@ -100,6 +100,7 @@ struct smuxed {
> #define CPG_CDDIV3 (0x40C)
> #define CPG_CDDIV4 (0x410)
> #define CPG_CSDIV0 (0x500)
> +#define CPG_CSDIV1 (0x504)
>
> #define CDDIV0_DIVCTL1 DDIV_PACK(CPG_CDDIV0, 4, 3, 1)
> #define CDDIV0_DIVCTL2 DDIV_PACK(CPG_CDDIV0, 8, 3, 2)
> @@ -168,6 +169,8 @@ enum clk_types {
> CLK_TYPE_PLL,
> CLK_TYPE_DDIV, /* Dynamic Switching Divider */
> CLK_TYPE_SMUX, /* Static Mux */
> + CLK_TYPE_PLLDSI, /* PLLDSI */
> + CLK_TYPE_PLLDSI_DIV, /* PLLDSI divider */
> };
>
> #define DEF_TYPE(_name, _id, _type...) \ @@ -195,6 +198,14 @@ enum clk_types
> {
> .num_parents = ARRAY_SIZE(_parent_names), \
> .flag = CLK_SET_RATE_PARENT, \
> .mux_flags = CLK_MUX_HIWORD_MASK)
> +#define DEF_PLLDSI(_name, _id, _parent, _pll_packed) \
> + DEF_TYPE(_name, _id, CLK_TYPE_PLLDSI, .parent = _parent, .cfg.pll =
> +_pll_packed) #define DEF_PLLDSI_DIV(_name, _id, _parent, _ddiv_packed,
> _dtable) \
> + DEF_TYPE(_name, _id, CLK_TYPE_PLLDSI_DIV, \
> + .cfg.ddiv = _ddiv_packed, \
> + .dtable = _dtable, \
> + .parent = _parent, \
> + .flag = CLK_SET_RATE_PARENT)
>
> /**
> * struct rzv2h_mod_clk - Module Clocks definitions @@ -295,6 +306,7 @@
> struct rzv2h_reset {
> *
> * @num_mstop_bits: Maximum number of MSTOP bits supported, equivalent to the
> * number of CPG_BUS_m_MSTOP registers multiplied by 16.
> + * @plldsi_limits: PLL DSI parameters limits
> */
> struct rzv2h_cpg_info {
> /* Core Clocks */
> @@ -313,6 +325,8 @@ struct rzv2h_cpg_info {
> unsigned int num_resets;
>
> unsigned int num_mstop_bits;
> +
> + const struct rzv2h_pll_div_limits *plldsi_limits;
> };
>
> extern const struct rzv2h_cpg_info r9a09g047_cpg_info; diff --git
> a/include/linux/clk/renesas-rzv2h-
> dsi.h b/include/linux/clk/renesas-rzv2h-dsi.h
> new file mode 100644
> index 000000000000..faecb5d49c20
> --- /dev/null
> +++ b/include/linux/clk/renesas-rzv2h-dsi.h
> @@ -0,0 +1,211 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * Renesas RZ/V2H(P) DSI CPG helper
> + *
> + * Copyright (C) 2025 Renesas Electronics Corp.
> + */
> +#ifndef __RENESAS_RZV2H_DSI_H__
> +#define __RENESAS_RZV2H_DSI_H__
> +
> +#include <linux/limits.h>
> +#include <linux/math.h>
> +#include <linux/math64.h>
> +#include <linux/units.h>
> +
> +#define OSC_CLK_IN_MEGA (24 * MEGA)
> +
> +struct rzv2h_pll_div_limits {
> + struct {
> + u32 min;
> + u32 max;
> + } fvco;
> +
> + struct {
> + u16 min;
> + u16 max;
> + } m;
> +
> + struct {
> + u8 min;
> + u8 max;
> + } p;
> +
> + struct {
> + u8 min;
> + u8 max;
> + } s;
> +
> + struct {
> + s16 min;
> + s16 max;
> + } k;
> +
> + struct {
> + u8 min;
> + u8 max;
> + } csdiv;
> +};
> +
> +struct rzv2h_plldsi_parameters {
> + u64 freq_millihz;
> + s64 error_millihz;
> + u16 m;
> + s16 k;
> + u8 csdiv;
> + u8 p;
> + u8 s;
> +};
> +
> +#define RZV2H_CPG_PLL_DSI_LIMITS(name)
> \
> + static const struct rzv2h_pll_div_limits (name) = { \
> + .fvco = { .min = 1600 * MEGA, .max = 3200 * MEGA }, \
> + .m = { .min = 64, .max = 533 }, \
> + .p = { .min = 1, .max = 4 }, \
> + .s = { .min = 0, .max = 6 }, \
> + .k = { .min = -32768, .max = 32767 }, \
> + .csdiv = { .min = 2, .max = 32 }, \
> + } \
> +
> +/**
> + * rzv2h_dsi_get_pll_parameters_values - Finds the best combination of
> +PLL parameters
> + * and divider value for a given frequency.
> + *
> + * @limits: Pointer to the structure containing the limits for the PLL
> +parameters and
> + * divider values
> + * @pars: Pointer to the structure where the best calculated PLL
> +parameters and divider
> + * values will be stored
> + * @freq_millihz: Target output frequency in millihertz
> + *
> + * This function calculates the best set of PLL parameters (M, K, P, S)
> +and divider
> + * value (CSDIV) to achieve the desired frequency.
> + * There is no direct formula to calculate the PLL parameters and the
> +divider value,
> + * as it's an open system of equations, therefore this function uses an
> +iterative
> + * approach to determine the best solution. The best solution is one
> +that minimizes
> + * the error (desired frequency - actual frequency).
> + *
> + * Return: true if a valid set of divider values is found, false otherwise.
> + */
> +static __maybe_unused bool
> +rzv2h_dsi_get_pll_parameters_values(const struct rzv2h_pll_div_limits
> *limits,
> + struct rzv2h_plldsi_parameters *pars,
> + u64 freq_millihz)
> +{
> + struct rzv2h_plldsi_parameters p, best;
> +
> + /* Initialize best error to maximum possible value */
> + best.error_millihz = S64_MAX;
> +
> + for (p.csdiv = limits->csdiv.min; p.csdiv <= limits->csdiv.max; p.csdiv
> += 2) {
> + for (p.p = limits->p.min; p.p <= limits->p.max; p.p++) {
> + u32 fref = OSC_CLK_IN_MEGA / p.p;
> +
> + for (p.s = limits->s.min; p.s <= limits->s.max; p.s++) {
> + u16 two_pow_s = 1 << p.s;
> + u16 divider = two_pow_s * p.csdiv;
> +
> + for (p.m = limits->m.min; p.m <= limits->m.max;
> p.m++) {
> + u64 output_m, output_k_range;
> + s64 pll_k, output_k;
> + u64 fvco, output;
> +
> + /*
> + * The frequency generated by the
> combination of the
> + * PLL + divider is calculated as
> follows:
> + *
> + * Freq = Ffout / csdiv
> + *
> + * With:
> + * Ffout = Ffvco / 2^(pll_s)
> + * Ffvco = (pll_m + (pll_k / 65536)) *
> Ffref
> + * Ffref = 24MHz / pll_p
> + *
> + * Freq can also be rewritten as:
> + * Freq = Ffvco / (2^(pll_s) * csdiv))
> + * = Ffvco / divider
> + * = (pll_m * Ffref) / divider +
> ((pll_k / 65536) * Ffref) /
> divider
> + * = output_m + output_k
> + *
> + * Every parameter has been determined
> at this point, but pll_k.
> + * Considering that:
> + * -32768 <= pll_k <= 32767
> + * Then:
> + * -0.5 <= (pll_k / 65536) < 0.5
> + * Therefore:
> + * -Ffref / (2 * divider) <= output_k <
> Ffref / (2 * divider)
> + */
> +
> + /* Compute output M component (in mHz)
> */
> + output_m = DIV_ROUND_CLOSEST_ULL(p.m *
> fref * 1000ULL,
> +
> divider);
> + /* Compute range for output K (in mHz)
> */
> + output_k_range =
> DIV_ROUND_CLOSEST_ULL(fref * 1000ULL,
> +
> divider * 2);
> + /*
> + * No point in continuing if we can't
> achieve the
> + * desired frequency
> + */
> + if (freq_millihz < (output_m -
> output_k_range) ||
> + freq_millihz >= (output_m +
> output_k_range))
> + continue;
> +
> + /*
> + * Compute the K component
> + *
> + * Since:
> + * Freq = output_m + output_k
> + * Then:
> + * output_k = Freq - output_m
> + * = ((pll_k / 65536) * Ffref)
> / divider
> + * Therefore:
> + * pll_k = (output_k * 65536 * divider)
> / Ffref
> + */
> + output_k = freq_millihz - output_m;
> + pll_k = div64_s64(output_k * 65536ULL *
> divider, fref);
> + pll_k = DIV_S64_ROUND_CLOSEST(pll_k,
> 1000);
> +
> + /* Validate K value within allowed
> limits */
> + if (pll_k < limits->k.min || pll_k >
> limits->k.max)
> + continue;
> +
> + p.k = pll_k;
> +
> + /* Compute (Ffvco * 65536) */
> + fvco = ((p.m * 65536ULL) + p.k) * fref;
> + if ((fvco < (limits->fvco.min *
> 65536ULL)) ||
> + (fvco > (limits->fvco.max *
> 65536ULL)))
> + continue;
> +
> + /* PLL_M component of (output * 65536 *
> PLL_P) */
> + output = p.m * 65536ULL *
> OSC_CLK_IN_MEGA;
> + /* PLL_K component of (output * 65536 *
> PLL_P) */
> + output += p.k * OSC_CLK_IN_MEGA;
> + /* Make it in mHz */
> + output *= 1000ULL;
> + output /= 65536ULL * p.p * divider;
> +
> + p.error_millihz = freq_millihz - output;
> + p.freq_millihz = output;
> +
> + /* If an exact match is found, return
> immediately */
> + if (p.error_millihz == 0) {
> + *pars = p;
> + return true;
> + }
> +
> + /* Update best match if error is
> smaller */
> + if (abs(best.error_millihz) >
> abs(p.error_millihz))
> + best = p;
> + }
> + }
> + }
> + }
> +
> + /* If no valid parameters were found, return false */
> + if (best.error_millihz == S64_MAX)
> + return false;
> +
> + *pars = best;
> + return true;
> +}
Are you ok with this approach? or some other generic method in clock Framework
to handle the milli Hertz ??
for eg: Maybe like introducing get and set to retrieve
the fractional part in clock Framework to handle the milli Hertz?
Cheers,
Biju
> +
> +#endif /* __RENESAS_RZV2H_DSI_H__ */
> --
> 2.49.0
