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Tue, 18 Nov 2025 14:08:10 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 0 X-BIZMAIL-ID: 8174621585258903689 EX-QQ-RecipientCnt: 13 From: Troy Mitchell Date: Tue, 18 Nov 2025 14:08:05 +0800 Subject: [PATCH v3 1/4] i2c: spacemit: configure ILCR for accurate SCL frequency Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20251118-p1-kconfig-fix-v3-1-8839c5ac5db3@linux.spacemit.com> References: <20251118-p1-kconfig-fix-v3-0-8839c5ac5db3@linux.spacemit.com> In-Reply-To: <20251118-p1-kconfig-fix-v3-0-8839c5ac5db3@linux.spacemit.com> To: Lee Jones , Yixun Lan , Alex Elder , Andi Shyti , Alexandre Belloni , Liam Girdwood , Mark Brown Cc: linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, spacemit@lists.linux.dev, linux-i2c@vger.kernel.org, linux-rtc@vger.kernel.org, Troy Mitchell X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1763446086; l=10890; i=troy.mitchell@linux.spacemit.com; s=20250710; h=from:subject:message-id; bh=gPxYVslgi88YMLvAgERRgcz+mantyYYzqxsNkcykFBw=; b=LTn6Nbq3SZ9QMLDywXOLC9OAU17X9ZJMLKA8i+/Z+yr6ykNBvAhYC+2/Ks5Ojb5gmMrHTl1Jz fDKqVX28k8+Cg95wpaApDFvfQ9ssDE/y2WUnSZDh5Unbg4luy4OxCCk X-Developer-Key: i=troy.mitchell@linux.spacemit.com; a=ed25519; pk=lQa7BzLrq8DfZnChqmwJ5qQk8fP2USmY/4xZ2/MSsXc= X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpsz:linux.spacemit.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: NafyJWIkf4MPiLqk+exutbgY8l+lOv7O9tHFvOHyawavxxQJgFiFHd1h S0IzXCFARteNxpi7A0Ny8TVTFEjby556scSFwdDP0esVeIZw1ZlJqfoiGYWMOhvVbluxfS2 TDzfD3nohRxsDvzLWDpAuHGEdgUDYHYRiraX1/MnN+UdY+E97CdlIIhs8jjQ9jUV11oil7J TiLXuCKndRkFTfn7jHZXctRviz7DI1ZxHWd6edUtI7e62SHVbB5iYhd6sKcLA9EkIfdBeep pXGyG7vSjDv6v0+FazjWpiAyLeyAFQrm72Doo1LFqWh5+HjDN1+eeT25WdqDcSd26279GxX HqtjbDpH9//LhQkMEahgRhQj+DdDloUgWlACTjDYT5jSdF+8wvRfx0OWEiROAgtu/LgwITV 6YnPMU/li5LCZDRNI4KkfVvnnJ8L8ndcLbS74cA9iYXvE38Dtvus1TENmPcSoF7dSXV2Qdc JEfMede/6lHgZ3yeD8anqQICb4+Rfd74U2PAoCVcdF3XlHBfppWVsy3+G+4/cWMp0eSQSAj 7HBTWfiPS3eyR/omEyLdN34gBNa/ITuXz56mR3ZMor/1ZaJvSgX7WSz+OYymxGGLDZhE6tR 42Z3Veab9FgPuPEDzUXvvNJZEI1KkG0BM4ktmtGUJHUfi+jgsCMvbowXDicJVZkni/8zGh6 SGPAIYIWFXBwUlYo9qne+JVwt5Y9NBWa7XduBAV5WCN5gSdqVtzPy+wJK9QCi8IQxArHjNp tHxOYWWA0hE4+A1nYvqcJusrABdDmVXsclehqrCfsEW7cbFMeusU2tWuORypqqmDv7PKiXz /ZBiscth2f/dxBrEW8Cy6jSB05Byajrz1e88XN4BG6hOQxFdUdQ1yQawiodtI+VCjrC1ea8 nu3cY7Z9YK++m1iy8Nw3HDcqwkrsdu6plfV+bHTRqXEZ9/36E3QFlTwK4o+MIyPQ+QGEVr6 SyMSDjQupY5XXyGzEOr5ygjsxj4gDZ1qNXX26r37wpAmT2AqzEnMoZwCpjCsb00r8r5zd/6 KxoyqqZdxPxg3cT0bT2f7QkmDlkkAtdKKf5mv7m6goWYq6sBoWcU2AUk8U+BdWMXh03jlbA JJQ5kyY+sYsSNKFwZMPlEry7OGtrQyrpi7aXpAb+AcTNA4XPFUjgJo15Cqxq0SjfqFBGOQ7 S59BzqRxW/VlC/k= X-QQ-XMRINFO: OWPUhxQsoeAVDbp3OJHYyFg= X-QQ-RECHKSPAM: 0 The SpacemiT I2C controller's SCL (Serial Clock Line) frequency for master mode operations is determined by the ILCR (I2C Load Count Register). Previously, the driver relied on the hardware's reset default values for this register. The hardware's default ILCR values (SLV=3D0x156, FLV=3D0x5d) yield SCL frequencies lower than intended. For example, with the default 31.5 MHz input clock, these default settings result in an SCL frequency of approximately 93 kHz (standard mode) when targeting 100 kHz, and approximately 338 kHz (fast mode) when targeting 400 kHz. These frequencies are below the 100 kHz/400 kHz nominal speeds. This patch integrates the SCL frequency management into the Common Clock Framework (CCF). Specifically, the ILCR register, which acts as a frequency divider for the SCL clock, is now registered as a managed clock (scl_clk) within the CCF. This patch also cleans up unnecessary whitespace in the included header files. Reviewed-by: Yixun Lan Link: https://lore.kernel.org/all/176244506110.1925720.10807118665958896958= .b4-ty@kernel.org/ [1] Signed-off-by: Troy Mitchell --- This patch was affected by the P1 Kconfig, which caused the maintainer to revert it. The current commit is a direct cherry-pick and reserves the original change= log. This note is to clarify for anyone who sees the cover letter marked as v2 while the changelog entries reach v4. --- Changelog in v4: - initialize clk_init_data with {} so that init.flags is implicitly set to 0 - minor cleanup and style fixes for better readability - remove unused spacemit_i2c_scl_clk_exclusive_put() cleanup callback - replace clk_set_rate_exclusive()/clk_rate_exclusive_put() pair with clk_s= et_rate() - simplify LCR LV field macros by using FIELD_GET/FIELD_MAX helpers - Link to v3: https://lore.kernel.org/all/20250814-k1-i2c-ilcr-v3-1-317723e= 74bcd@linux.spacemit.com/ Changelog in v3: - use MASK macro in `recalc_rate` function - rename clock name - Link to v2: https://lore.kernel.org/r/20250718-k1-i2c-ilcr-v2-1-b4c68f13d= cb1@linux.spacemit.com Changelog in v2: - Align line breaks. - Check `lv` in `clk_set_rate` function. - Force fast mode when SCL frequency is illegal or unavailable. - Change "linux/bits.h" to - Kconfig: Add dependency on CCF. - Link to v1: https://lore.kernel.org/all/20250710-k1-i2c-ilcr-v1-1-188d1f4= 60c7d@linux.spacemit.com/ --- drivers/i2c/busses/Kconfig | 2 +- drivers/i2c/busses/i2c-k1.c | 159 ++++++++++++++++++++++++++++++++++++++++= ---- 2 files changed, 146 insertions(+), 15 deletions(-) diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig index fd81e49638aaa161ae264a722e9e06adc7914cda..fedf5d31f9035b73a27a7f8a764= bf5c26975d0e1 100644 --- a/drivers/i2c/busses/Kconfig +++ b/drivers/i2c/busses/Kconfig @@ -798,7 +798,7 @@ config I2C_JZ4780 config I2C_K1 tristate "SpacemiT K1 I2C adapter" depends on ARCH_SPACEMIT || COMPILE_TEST - depends on OF + depends on OF && COMMON_CLK help This option enables support for the I2C interface on the SpacemiT K1 platform. diff --git a/drivers/i2c/busses/i2c-k1.c b/drivers/i2c/busses/i2c-k1.c index 6b918770e612e098b8ad17418f420d87c94df166..e38a0ba71734ca602854c85672d= cb61423453515 100644 --- a/drivers/i2c/busses/i2c-k1.c +++ b/drivers/i2c/busses/i2c-k1.c @@ -4,18 +4,21 @@ */ =20 #include - #include - #include - #include - #include - #include - #include +#include +#include +#include +#include +#include +#include +#include +#include =20 /* spacemit i2c registers */ #define SPACEMIT_ICR 0x0 /* Control register */ #define SPACEMIT_ISR 0x4 /* Status register */ #define SPACEMIT_IDBR 0xc /* Data buffer register */ #define SPACEMIT_IRCR 0x18 /* Reset cycle counter */ +#define SPACEMIT_ILCR 0x10 /* Load Count Register */ #define SPACEMIT_IBMR 0x1c /* Bus monitor register */ =20 /* SPACEMIT_ICR register fields */ @@ -87,6 +90,13 @@ #define SPACEMIT_BMR_SDA BIT(0) /* SDA line level */ #define SPACEMIT_BMR_SCL BIT(1) /* SCL line level */ =20 +#define SPACEMIT_LCR_LV_STANDARD_SHIFT 0 +#define SPACEMIT_LCR_LV_FAST_SHIFT 9 +#define SPACEMIT_LCR_LV_STANDARD_MASK GENMASK(8, 0) +#define SPACEMIT_LCR_LV_FAST_MASK GENMASK(17, 9) +#define SPACEMIT_LCR_LV_STANDARD_MAX_VALUE FIELD_MAX(SPACEMIT_LCR_LV_STAND= ARD_MASK) +#define SPACEMIT_LCR_LV_FAST_MAX_VALUE FIELD_MAX(SPACEMIT_LCR_LV_FAST_MAS= K) + /* i2c bus recover timeout: us */ #define SPACEMIT_I2C_BUS_BUSY_TIMEOUT 100000 =20 @@ -104,11 +114,20 @@ enum spacemit_i2c_state { SPACEMIT_STATE_WRITE, }; =20 +enum spacemit_i2c_mode { + SPACEMIT_MODE_STANDARD, + SPACEMIT_MODE_FAST +}; + /* i2c-spacemit driver's main struct */ struct spacemit_i2c_dev { struct device *dev; struct i2c_adapter adapt; =20 + struct clk_hw scl_clk_hw; + struct clk *scl_clk; + enum spacemit_i2c_mode mode; + /* hardware resources */ void __iomem *base; int irq; @@ -129,6 +148,79 @@ struct spacemit_i2c_dev { u32 status; }; =20 +static void spacemit_i2c_scl_clk_disable_unprepare(void *data) +{ + struct spacemit_i2c_dev *i2c =3D data; + + clk_disable_unprepare(i2c->scl_clk); +} + +static int spacemit_i2c_clk_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct spacemit_i2c_dev *i2c =3D container_of(hw, struct spacemit_i2c_dev= , scl_clk_hw); + u32 lv, lcr, mask, shift, max_lv; + + lv =3D DIV_ROUND_UP(parent_rate, rate); + + if (i2c->mode =3D=3D SPACEMIT_MODE_STANDARD) { + mask =3D SPACEMIT_LCR_LV_STANDARD_MASK; + shift =3D SPACEMIT_LCR_LV_STANDARD_SHIFT; + max_lv =3D SPACEMIT_LCR_LV_STANDARD_MAX_VALUE; + } else if (i2c->mode =3D=3D SPACEMIT_MODE_FAST) { + mask =3D SPACEMIT_LCR_LV_FAST_MASK; + shift =3D SPACEMIT_LCR_LV_FAST_SHIFT; + max_lv =3D SPACEMIT_LCR_LV_FAST_MAX_VALUE; + } + + if (!lv || lv > max_lv) { + dev_err(i2c->dev, "set scl clock failed: lv 0x%x", lv); + return -EINVAL; + } + + lcr =3D readl(i2c->base + SPACEMIT_ILCR); + lcr &=3D ~mask; + lcr |=3D lv << shift; + writel(lcr, i2c->base + SPACEMIT_ILCR); + + return 0; +} + +static long spacemit_i2c_clk_round_rate(struct clk_hw *hw, unsigned long r= ate, + unsigned long *parent_rate) +{ + u32 lv, freq; + + lv =3D DIV_ROUND_UP(*parent_rate, rate); + freq =3D DIV_ROUND_UP(*parent_rate, lv); + + return freq; +} + +static unsigned long spacemit_i2c_clk_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct spacemit_i2c_dev *i2c =3D container_of(hw, struct spacemit_i2c_dev= , scl_clk_hw); + u32 lcr, lv =3D 0; + + lcr =3D readl(i2c->base + SPACEMIT_ILCR); + + if (i2c->mode =3D=3D SPACEMIT_MODE_STANDARD) + lv =3D FIELD_GET(SPACEMIT_LCR_LV_STANDARD_MASK, lcr); + else if (i2c->mode =3D=3D SPACEMIT_MODE_FAST) + lv =3D FIELD_GET(SPACEMIT_LCR_LV_FAST_MASK, lcr); + else + return 0; + + return DIV_ROUND_UP(parent_rate, lv); +} + +static const struct clk_ops spacemit_i2c_clk_ops =3D { + .set_rate =3D spacemit_i2c_clk_set_rate, + .round_rate =3D spacemit_i2c_clk_round_rate, + .recalc_rate =3D spacemit_i2c_clk_recalc_rate, +}; + static void spacemit_i2c_enable(struct spacemit_i2c_dev *i2c) { u32 val; @@ -147,6 +239,26 @@ static void spacemit_i2c_disable(struct spacemit_i2c_d= ev *i2c) writel(val, i2c->base + SPACEMIT_ICR); } =20 +static struct clk *spacemit_i2c_register_scl_clk(struct spacemit_i2c_dev *= i2c, + struct clk *parent) +{ + struct clk_init_data init =3D {}; + char name[32]; + + snprintf(name, sizeof(name), "%s_scl_clk", dev_name(i2c->dev)); + + init.name =3D name; + init.ops =3D &spacemit_i2c_clk_ops; + init.parent_data =3D (struct clk_parent_data[]) { + { .fw_name =3D "func" }, + }; + init.num_parents =3D 1; + + i2c->scl_clk_hw.init =3D &init; + + return devm_clk_register(i2c->dev, &i2c->scl_clk_hw); +} + static void spacemit_i2c_reset(struct spacemit_i2c_dev *i2c) { writel(SPACEMIT_CR_UR, i2c->base + SPACEMIT_ICR); @@ -246,7 +358,7 @@ static void spacemit_i2c_init(struct spacemit_i2c_dev *= i2c) */ val |=3D SPACEMIT_CR_DRFIE; =20 - if (i2c->clock_freq =3D=3D SPACEMIT_I2C_MAX_FAST_MODE_FREQ) + if (i2c->mode =3D=3D SPACEMIT_MODE_FAST) val |=3D SPACEMIT_CR_MODE_FAST; =20 /* disable response to general call */ @@ -538,14 +650,15 @@ static int spacemit_i2c_probe(struct platform_device = *pdev) dev_warn(dev, "failed to read clock-frequency property: %d\n", ret); =20 /* For now, this driver doesn't support high-speed. */ - if (!i2c->clock_freq || i2c->clock_freq > SPACEMIT_I2C_MAX_FAST_MODE_FREQ= ) { - dev_warn(dev, "unsupported clock frequency %u; using %u\n", - i2c->clock_freq, SPACEMIT_I2C_MAX_FAST_MODE_FREQ); + if (i2c->clock_freq > SPACEMIT_I2C_MAX_STANDARD_MODE_FREQ && + i2c->clock_freq <=3D SPACEMIT_I2C_MAX_FAST_MODE_FREQ) { + i2c->mode =3D SPACEMIT_MODE_FAST; + } else if (i2c->clock_freq && i2c->clock_freq <=3D SPACEMIT_I2C_MAX_STAND= ARD_MODE_FREQ) { + i2c->mode =3D SPACEMIT_MODE_STANDARD; + } else { + dev_warn(i2c->dev, "invalid clock-frequency, fallback to fast mode"); + i2c->mode =3D SPACEMIT_MODE_FAST; i2c->clock_freq =3D SPACEMIT_I2C_MAX_FAST_MODE_FREQ; - } else if (i2c->clock_freq < SPACEMIT_I2C_MAX_STANDARD_MODE_FREQ) { - dev_warn(dev, "unsupported clock frequency %u; using %u\n", - i2c->clock_freq, SPACEMIT_I2C_MAX_STANDARD_MODE_FREQ); - i2c->clock_freq =3D SPACEMIT_I2C_MAX_STANDARD_MODE_FREQ; } =20 i2c->dev =3D &pdev->dev; @@ -567,10 +680,28 @@ static int spacemit_i2c_probe(struct platform_device = *pdev) if (IS_ERR(clk)) return dev_err_probe(dev, PTR_ERR(clk), "failed to enable func clock"); =20 + i2c->scl_clk =3D spacemit_i2c_register_scl_clk(i2c, clk); + if (IS_ERR(i2c->scl_clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(i2c->scl_clk), + "failed to register scl clock\n"); + clk =3D devm_clk_get_enabled(dev, "bus"); if (IS_ERR(clk)) return dev_err_probe(dev, PTR_ERR(clk), "failed to enable bus clock"); =20 + ret =3D clk_set_rate(i2c->scl_clk, i2c->clock_freq); + if (ret) + return dev_err_probe(&pdev->dev, ret, "failed to set rate for SCL clock"= ); + + ret =3D clk_prepare_enable(i2c->scl_clk); + if (ret) + return dev_err_probe(&pdev->dev, ret, "failed to prepare and enable cloc= k"); + + ret =3D devm_add_action_or_reset(dev, spacemit_i2c_scl_clk_disable_unprep= are, i2c); + if (ret) + return dev_err_probe(&pdev->dev, ret, + "failed to register cleanup action for clk disable and unprepare"= ); + spacemit_i2c_reset(i2c); =20 i2c_set_adapdata(&i2c->adapt, i2c); --=20 2.51.2