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[93.34.92.187]) by smtp.googlemail.com with ESMTPSA id ffacd0b85a97d-48e71b78c10sm1489936f8f.25.2026.10.30.00.13.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 30 Oct 2026 00:13:40 -0700 (PDT) From: Christian Marangi To: Stefan Roese , Andi Shyti , Matthias Brugger , AngeloGioacchino Del Regno , linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org Cc: Christian Marangi Subject: [PATCH v4] i2c: mt7621: rework cmd/wait OPs to support atomic afer variant Date: Fri, 30 Oct 2026 08:13:23 +0100 Message-ID: <20261030071325.2678-1-ansuelsmth@gmail.com> X-Mailer: git-send-email 2.55.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit It was reported the need for atomic operation on some Airoha SoC that makes use of I2C bus. Rework the cmd/wait OPs to suppor the xfer_atomic variant. To support this it's needed to do the readl poll in atomic context and special handling for device_reset. Signed-off-by: Christian Marangi --- Changes v4: - Split to dedicated patch - Reduce timeout to 250ms - Disable device_reset in atomic context Changes v3..v2: - No related changes drivers/i2c/busses/i2c-mt7621.c | 75 ++++++++++++++++++++++----------- 1 file changed, 51 insertions(+), 24 deletions(-) diff --git a/drivers/i2c/busses/i2c-mt7621.c b/drivers/i2c/busses/i2c-mt7621.c index 9ea5e3f9a763..0283191ac518 100644 --- a/drivers/i2c/busses/i2c-mt7621.c +++ b/drivers/i2c/busses/i2c-mt7621.c @@ -67,27 +67,38 @@ struct mtk_i2c { struct clk *clk; }; -static int mtk_i2c_wait_idle(struct mtk_i2c *i2c) +static int mtk_i2c_wait_idle(struct mtk_i2c *i2c, bool atomic) { int ret; u32 val; - ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG, - val, !(val & SM0CTL1_TRI), - 10, TIMEOUT_MS * 1000); + if (atomic) + ret = readl_relaxed_poll_timeout_atomic(i2c->base + REG_SM0CTL1_REG, + val, !(val & SM0CTL1_TRI), + 10, TIMEOUT_MS * 250); + else + ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG, + val, !(val & SM0CTL1_TRI), + 10, TIMEOUT_MS * 1000); if (ret) dev_dbg(i2c->dev, "idle err(%d)\n", ret); return ret; } -static void mtk_i2c_reset(struct mtk_i2c *i2c) +static void mtk_i2c_reset(struct mtk_i2c *i2c, bool atomic) { int ret; - ret = device_reset(i2c->adap.dev.parent); - if (ret) - dev_err(i2c->dev, "I2C reset failed!\n"); + /* + * Skip device_reset in atomic context as it depends on the + * reset-controller correctly handling atomic operations. + */ + if (!atomic) { + ret = device_reset(i2c->adap.dev.parent); + if (ret) + dev_err(i2c->dev, "I2C reset failed!\n"); + } /* * Don't set SM0CTL0_ODRAIN as its bit meaning is inverted. To @@ -117,27 +128,28 @@ static int mtk_i2c_check_ack(struct mtk_i2c *i2c, u32 expected) return ((ack & ack_expected) == ack_expected) ? 0 : -ENXIO; } -static int mtk_i2c_start(struct mtk_i2c *i2c) +static int mtk_i2c_start(struct mtk_i2c *i2c, bool atomic) { iowrite32(SM0CTL1_START | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG); - return mtk_i2c_wait_idle(i2c); + return mtk_i2c_wait_idle(i2c, atomic); } -static int mtk_i2c_stop(struct mtk_i2c *i2c) +static int mtk_i2c_stop(struct mtk_i2c *i2c, bool atomic) { iowrite32(SM0CTL1_STOP | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG); - return mtk_i2c_wait_idle(i2c); + return mtk_i2c_wait_idle(i2c, atomic); } -static int mtk_i2c_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len) +static int mtk_i2c_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len, + bool atomic) { iowrite32(cmd | SM0CTL1_TRI | SM0CTL1_PGLEN(page_len), i2c->base + REG_SM0CTL1_REG); - return mtk_i2c_wait_idle(i2c); + return mtk_i2c_wait_idle(i2c, atomic); } -static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, - int num) +static int mtk_i2c_xfer_common(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num, bool atomic) { struct mtk_i2c *i2c; struct i2c_msg *pmsg; @@ -151,12 +163,12 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, pmsg = &msgs[i]; /* wait hardware idle */ - ret = mtk_i2c_wait_idle(i2c); + ret = mtk_i2c_wait_idle(i2c, atomic); if (ret) goto err_timeout; /* start sequence */ - ret = mtk_i2c_start(i2c); + ret = mtk_i2c_start(i2c, atomic); if (ret) goto err_timeout; @@ -172,7 +184,8 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, len = 1; } iowrite32(addr, i2c->base + REG_SM0D0_REG); - ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, len); + ret = mtk_i2c_cmd(i2c, SM0CTL1_WRITE, len, + atomic); if (ret) goto err_timeout; @@ -200,7 +213,7 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, cmd = SM0CTL1_WRITE; } - ret = mtk_i2c_cmd(i2c, cmd, page_len); + ret = mtk_i2c_cmd(i2c, cmd, page_len, atomic); if (ret) goto err_timeout; @@ -221,7 +234,7 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, } } - ret = mtk_i2c_stop(i2c); + ret = mtk_i2c_stop(i2c, atomic); if (ret) goto err_timeout; @@ -229,17 +242,30 @@ static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, return i; err_ack: - ret = mtk_i2c_stop(i2c); + ret = mtk_i2c_stop(i2c, atomic); if (ret) goto err_timeout; return -ENXIO; err_timeout: mtk_i2c_dump_reg(i2c); - mtk_i2c_reset(i2c); + mtk_i2c_reset(i2c, atomic); + return ret; } +static int mtk_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + return mtk_i2c_xfer_common(adap, msgs, num, false); +} + +static int mtk_i2c_xfer_atomic(struct i2c_adapter *adap, + struct i2c_msg *msgs, int num) +{ + return mtk_i2c_xfer_common(adap, msgs, num, true); +} + static u32 mtk_i2c_func(struct i2c_adapter *a) { return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING; @@ -247,6 +273,7 @@ static u32 mtk_i2c_func(struct i2c_adapter *a) static const struct i2c_algorithm mtk_i2c_algo = { .xfer = mtk_i2c_xfer, + .xfer_atomic = mtk_i2c_xfer_atomic, .functionality = mtk_i2c_func, }; @@ -265,7 +292,7 @@ static void mtk_i2c_init(struct mtk_i2c *i2c) if (i2c->clk_div > SM0CTL0_CLK_DIV_MAX) i2c->clk_div = SM0CTL0_CLK_DIV_MAX; - mtk_i2c_reset(i2c); + mtk_i2c_reset(i2c, false); } static int mtk_i2c_probe(struct platform_device *pdev) -- 2.55.0