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([2.196.42.147]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38be66b01c7sm278970f8f.22.2025.01.14.10.20.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jan 2025 10:20:31 -0800 (PST) From: Dario Binacchi To: linux-kernel@vger.kernel.org Cc: linux-amarula@amarulasolutions.com, Dario Binacchi , Alexandre Torgue , Maxime Coquelin , Michael Turquette , Stephen Boyd , linux-arm-kernel@lists.infradead.org, linux-clk@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com Subject: [PATCH v4 4/4] clk: stm32f4: support spread spectrum clock generation Date: Tue, 14 Jan 2025 19:19:49 +0100 Message-ID: <20250114182021.670435-5-dario.binacchi@amarulasolutions.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250114182021.670435-1-dario.binacchi@amarulasolutions.com> References: <20250114182021.670435-1-dario.binacchi@amarulasolutions.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Support spread spectrum clock generation for the main PLL, the only one for which this functionality is available. Tested on the STM32F469I-DISCO board. Signed-off-by: Dario Binacchi --- Changes in v4: - Improve the compatible property in patch 1/4 "dt-bindings: clock: convert stm32 rcc bindings to json-schema" Changes in v3: - Changes to patch 4/4 "clk: stm32f4: support spread spectrum clock generat= ion" according to Stephen Boyd's suggestions. - Drop pr_debug() from stm32f4_pll_set_ssc() - Add __init to stm32f4_pll_init_ssc() and stm32f4_pll_ssc_parse_dt(). - Add const to conf parameter of stm32f4_pll_init_ssc(). - Use fwnode_property_match_property_string() to parse the st,ssc-modmethod dts property. Changes in v2: - Fixup patches: 2/6 dt-bindings: reset: st,stm32-rcc: update reference due to rename 3/6 dt-bindings: clock: stm32fx: update reference due to rename to 1/6 dt-bindings: clock: convert stm32 rcc bindings to json-schema - Changes to dt-bindings: clock: convert stm32 rcc bindings to json-schema - Changes to dt-bindings: clock: st,stm32-rcc: support spread spectrum cloc= king drivers/clk/clk-stm32f4.c | 143 +++++++++++++++++++++++++++++++++++++- 1 file changed, 140 insertions(+), 3 deletions(-) diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c index db1c56c8d54f..f476883bc93b 100644 --- a/drivers/clk/clk-stm32f4.c +++ b/drivers/clk/clk-stm32f4.c @@ -35,6 +35,7 @@ #define STM32F4_RCC_APB2ENR 0x44 #define STM32F4_RCC_BDCR 0x70 #define STM32F4_RCC_CSR 0x74 +#define STM32F4_RCC_SSCGR 0x80 #define STM32F4_RCC_PLLI2SCFGR 0x84 #define STM32F4_RCC_PLLSAICFGR 0x88 #define STM32F4_RCC_DCKCFGR 0x8c @@ -42,6 +43,12 @@ =20 #define STM32F4_RCC_PLLCFGR_N_MASK GENMASK(14, 6) =20 +#define STM32F4_RCC_SSCGR_SSCGEN BIT(31) +#define STM32F4_RCC_SSCGR_SPREADSEL BIT(30) +#define STM32F4_RCC_SSCGR_RESERVED_MASK GENMASK(29, 28) +#define STM32F4_RCC_SSCGR_INCSTEP_MASK GENMASK(27, 13) +#define STM32F4_RCC_SSCGR_MODPER_MASK GENMASK(12, 0) + #define NONE -1 #define NO_IDX NONE #define NO_MUX NONE @@ -367,6 +374,16 @@ static const struct stm32f4_gate_data stm32f769_gates[= ] __initconst =3D { { STM32F4_RCC_APB2ENR, 30, "mdio", "apb2_div" }, }; =20 +enum stm32f4_pll_ssc_mod_type { + STM32F4_PLL_SSC_CENTER_SPREAD, + STM32F4_PLL_SSC_DOWN_SPREAD, +}; + +static const char * const stm32f4_ssc_mod_methods[] __initconst =3D { + [STM32F4_PLL_SSC_DOWN_SPREAD] =3D "down-spread", + [STM32F4_PLL_SSC_CENTER_SPREAD] =3D "center-spread", +}; + /* * This bitmask tells us which bit offsets (0..192) on STM32F4[23]xxx * have gate bits associated with them. Its combined hweight is 71. @@ -512,6 +529,12 @@ static const struct clk_div_table pll_divr_table[] =3D= { { 2, 2 }, { 3, 3 }, { 4, 4 }, { 5, 5 }, { 6, 6 }, { 7, 7 }, { 0 } }; =20 +struct stm32f4_pll_ssc { + unsigned int mod_freq; + unsigned int mod_depth; + enum stm32f4_pll_ssc_mod_type mod_type; +}; + struct stm32f4_pll { spinlock_t *lock; struct clk_gate gate; @@ -519,6 +542,8 @@ struct stm32f4_pll { u8 bit_rdy_idx; u8 status; u8 n_start; + bool ssc_enable; + struct stm32f4_pll_ssc ssc_conf; }; =20 #define to_stm32f4_pll(_gate) container_of(_gate, struct stm32f4_pll, gate) @@ -541,6 +566,7 @@ struct stm32f4_vco_data { u8 offset; u8 bit_idx; u8 bit_rdy_idx; + bool sscg; }; =20 static const struct stm32f4_vco_data vco_data[] =3D { @@ -661,6 +687,32 @@ static long stm32f4_pll_round_rate(struct clk_hw *hw, = unsigned long rate, return *prate * n; } =20 +static void stm32f4_pll_set_ssc(struct clk_hw *hw, unsigned long parent_ra= te, + unsigned int ndiv) +{ + struct clk_gate *gate =3D to_clk_gate(hw); + struct stm32f4_pll *pll =3D to_stm32f4_pll(gate); + struct stm32f4_pll_ssc *ssc =3D &pll->ssc_conf; + u32 modeper, incstep; + u32 sscgr; + + sscgr =3D readl(base + STM32F4_RCC_SSCGR); + /* reserved field must be kept at reset value */ + sscgr &=3D STM32F4_RCC_SSCGR_RESERVED_MASK; + + modeper =3D DIV_ROUND_CLOSEST(parent_rate, 4 * ssc->mod_freq); + incstep =3D DIV_ROUND_CLOSEST(((1 << 15) - 1) * ssc->mod_depth * ndiv, + 5 * 10000 * modeper); + sscgr |=3D STM32F4_RCC_SSCGR_SSCGEN | + FIELD_PREP(STM32F4_RCC_SSCGR_INCSTEP_MASK, incstep) | + FIELD_PREP(STM32F4_RCC_SSCGR_MODPER_MASK, modeper); + + if (ssc->mod_type) + sscgr |=3D STM32F4_RCC_SSCGR_SPREADSEL; + + writel(sscgr, base + STM32F4_RCC_SSCGR); +} + static int stm32f4_pll_set_rate(struct clk_hw *hw, unsigned long rate, unsigned long parent_rate) { @@ -683,6 +735,9 @@ static int stm32f4_pll_set_rate(struct clk_hw *hw, unsi= gned long rate, =20 writel(val, base + pll->offset); =20 + if (pll->ssc_enable) + stm32f4_pll_set_ssc(hw, parent_rate, n); + if (pll_state) stm32f4_pll_enable(hw); =20 @@ -788,6 +843,84 @@ static struct clk_hw *clk_register_pll_div(const char = *name, return hw; } =20 +static int __init stm32f4_pll_init_ssc(struct clk_hw *hw, + const struct stm32f4_pll_ssc *conf) +{ + struct clk_gate *gate =3D to_clk_gate(hw); + struct stm32f4_pll *pll =3D to_stm32f4_pll(gate); + struct clk_hw *parent; + unsigned long parent_rate; + int pll_state; + unsigned long n, val; + + parent =3D clk_hw_get_parent(hw); + if (!parent) { + pr_err("%s: failed to get clock parent\n", __func__); + return -ENODEV; + } + + parent_rate =3D clk_hw_get_rate(parent); + + pll->ssc_enable =3D true; + memcpy(&pll->ssc_conf, conf, sizeof(pll->ssc_conf)); + + pll_state =3D stm32f4_pll_is_enabled(hw); + + if (pll_state) + stm32f4_pll_disable(hw); + + val =3D readl(base + pll->offset); + n =3D FIELD_GET(STM32F4_RCC_PLLCFGR_N_MASK, val); + + pr_debug("%s: pll: %s, parent: %s, parent-rate: %lu, n: %lu\n", + __func__, clk_hw_get_name(hw), clk_hw_get_name(parent), + parent_rate, n); + + stm32f4_pll_set_ssc(hw, parent_rate, n); + + if (pll_state) + stm32f4_pll_enable(hw); + + return 0; +} + +static int __init stm32f4_pll_ssc_parse_dt(struct device_node *np, + struct stm32f4_pll_ssc *conf) +{ + int ret; + const char *s; + + if (!conf) + return -EINVAL; + + ret =3D of_property_read_u32(np, "st,ssc-modfreq-hz", &conf->mod_freq); + if (ret) + return ret; + + ret =3D of_property_read_u32(np, "st,ssc-moddepth-permyriad", + &conf->mod_depth); + if (ret) { + pr_err("%pOF: missing st,ssc-moddepth-permyriad\n", np); + return ret; + } + + ret =3D fwnode_property_match_property_string(of_fwnode_handle(np), + "st,ssc-modmethod", + stm32f4_ssc_mod_methods, + ARRAY_SIZE(stm32f4_ssc_mod_methods)); + if (ret < 0) { + pr_err("%pOF: failed to get st,ssc-modmethod\n", np); + return ret; + } + + conf->mod_type =3D ret; + + pr_debug("%pOF: SSCG settings: mod_freq: %d, mod_depth: %d mod_method: %s= [%d]\n", + np, conf->mod_freq, conf->mod_depth, s, conf->mod_type); + + return 0; +} + static struct clk_hw *stm32f4_rcc_register_pll(const char *pllsrc, const struct stm32f4_pll_data *data, spinlock_t *lock) { @@ -1695,7 +1828,8 @@ static void __init stm32f4_rcc_init(struct device_nod= e *np) const struct of_device_id *match; const struct stm32f4_clk_data *data; unsigned long pllm; - struct clk_hw *pll_src_hw; + struct clk_hw *pll_src_hw, *pll_vco_hw; + struct stm32f4_pll_ssc ssc_conf; =20 base =3D of_iomap(np, 0); if (!base) { @@ -1754,8 +1888,8 @@ static void __init stm32f4_rcc_init(struct device_nod= e *np) clk_hw_register_fixed_factor(NULL, "vco_in", pll_src, 0, 1, pllm); =20 - stm32f4_rcc_register_pll("vco_in", &data->pll_data[0], - &stm32f4_clk_lock); + pll_vco_hw =3D stm32f4_rcc_register_pll("vco_in", &data->pll_data[0], + &stm32f4_clk_lock); =20 clks[PLL_VCO_I2S] =3D stm32f4_rcc_register_pll("vco_in", &data->pll_data[1], &stm32f4_clk_lock); @@ -1900,6 +2034,9 @@ static void __init stm32f4_rcc_init(struct device_nod= e *np) =20 of_clk_add_hw_provider(np, stm32f4_rcc_lookup_clk, NULL); =20 + if (!stm32f4_pll_ssc_parse_dt(np, &ssc_conf)) + stm32f4_pll_init_ssc(pll_vco_hw, &ssc_conf); + return; fail: kfree(clks); --=20 2.43.0