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Fri, 17 Oct 2025 15:27:47 +0800 (CST) X-QQ-SSF: 0000000000000000000000000000000 X-QQ-GoodBg: 0 X-BIZMAIL-ID: 2983751479809764245 EX-QQ-RecipientCnt: 7 From: Troy Mitchell Date: Fri, 17 Oct 2025 15:27:39 +0800 Subject: [PATCH v4] 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: <20251017-k1-i2c-ilcr-v4-1-eed4903ecdb9@linux.spacemit.com> X-B4-Tracking: v=1; b=H4sIAOrv8WgC/6tWKk4tykwtVrJSqFYqSi3LLM7MzwNyTHQUlJIzE vPSU3UzU4B8JSMDI1NDA0Nz3WxD3UyjZN3MnOQi3WRLI4sUU4NUEwPzNCWgjoKi1LTMCrBp0bG 1tQBzn/6OXQAAAA== X-Change-ID: 20251017-k1-i2c-ilcr-c928d50e407f To: Andi Shyti , Yixun Lan Cc: linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, spacemit@lists.linux.dev, Troy Mitchell X-Mailer: b4 0.14.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1760686067; l=10627; i=troy.mitchell@linux.spacemit.com; s=20250710; h=from:subject:message-id; bh=k7izFLZOtX/Py2xq/tvUTB74MWgsPUMPXbHHgh+Chu4=; b=ByADNB/Eak52WxCnpxkeTUU8hnGwPG06+OUjTA6GZaQcog4YS8krwnnAOj6JfbtQUwwkaKucu 7O2zuvRgfEFAwJ6WnbDel+rfbI9zLIWviVKbyxTswFKtG7vpmjWeJqo X-Developer-Key: i=troy.mitchell@linux.spacemit.com; a=ed25519; pk=lQa7BzLrq8DfZnChqmwJ5qQk8fP2USmY/4xZ2/MSsXc= X-QQ-SENDSIZE: 520 Feedback-ID: zesmtpgz:linux.spacemit.com:qybglogicsvrgz:qybglogicsvrgz3a-0 X-QQ-XMAILINFO: MTg7kbcnv4eHunCH2h0Eykl3mYFwY6Euvx7w+uo4CS2qP48DJ2J4xh52 OrKtzKYvU14K7tFPVbW1oTTyr62yyU2Qd6IJud7SvFxB4nuKlAkF1dEczGp0Z5c49jQ/Wok C29Erw5hYzDThDIhy/YIXIxMZme/ekkGaxF6W2hcURswwILtOK0cyU3KTa7B7UpzotpP5uq aMUCJZMNPmRddKSPSXwW8sU2D6R5HK9jSNAa9GAxqJNMv3vJQL17leaKb79+5vt8gx9KXRH 6Mnz/nz/LePUpptNPLZB+Aq3MoNMyTQmGLxDlixJGlqsbZaE06K9x8PVLe1pgrClYSA+Ylv QUjDd6bUu+WB1dyMRI6332DgD1iJ4L8KgztFfoocYS6MQQkLiZna8Dn2KWyw6YKAsjElMY7 7JA5k/INPIat1bq5FNtgpD+rSU1tRb8f5m411xflfIcK/BI+WZA8nennNT25Xk3MzXI+u3c UWL0wLgBKdsHyW8mvruA58ggVweDfg6FMYX93BwYhSeco0tMr6fxIwM6E/FQyOKbo5gjvG/ TFkcbctqRCIhzs8k7kEOzMPZ40AGGEwd71a2eHJKmFy6Az8GJUjDMRYDsNVu2Um481IRACp fYmMsPM5CP3YNCMYX6JD760SQtD3ggsnHQgY7GSck5qtMH1ghAxahUhitLtCP5UwU7PVLkG EdlSiuykQCOCS1MNgIFLQ8f1u8bNDDjaxiZCHpDAYGqc6AAhG8nbYbMZet1EveUB+w747Ij UWJjd60Uf/vx3TFQrvrgaOullZgJMmpii6XUWVlfN6kMfO38sc8LUHJU06jLeKeESsPuCDp SuKS3fYXdkwvL6walVC9EADaLxDYCeouJDhNKCswS4oSneRY3l2nNIVM+6fgnBbKV9Aw8x/ SkfbO+YurcD00RwsuyGRi/gzTmKvLdfy8kOvYug+O2Tpu1bJla7SQ1NgVVGujd9RNlWC9TK +QG9gBiOoI2tDbMOHKK3UCFh5BuxnfDPREEvE348zvnHZ9Rfu862+fxMgt1JRcmAgKIMeEm JawQLFOeED0gm62cdNdnNiQ2A2rBz4+JjfMi2PAXntpGvEdYGIVHd96ObML6Bd3hh4ol3AC 9PZ4jj92CaM X-QQ-XMRINFO: Nq+8W0+stu50PRdwbJxPCL0= 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. Signed-off-by: Troy Mitchell Reviewed-by: Yixun Lan --- 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); --- base-commit: 316cb41c2400fbc0584aca75be78556914b66272 change-id: 20251017-k1-i2c-ilcr-c928d50e407f Best regards, --=20 Troy Mitchell