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Wed, 15 Jan 2020 04:54:46 -0700 Received: from rob-ult-m19940.microchip.com (10.10.85.251) by chn-vm-ex03.mchp-main.com (10.10.85.151) with Microsoft SMTP Server id 15.1.1713.5 via Frontend Transport; Wed, 15 Jan 2020 04:54:43 -0700 From: Codrin Ciubotariu To: , , , Subject: [PATCH v3 2/6] i2c: at91: implement i2c bus recovery Date: Wed, 15 Jan 2020 13:54:18 +0200 Message-ID: <20200115115422.17097-3-codrin.ciubotariu@microchip.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200115115422.17097-1-codrin.ciubotariu@microchip.com> References: <20200115115422.17097-1-codrin.ciubotariu@microchip.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200115_035451_456901_121F64D3 X-CRM114-Status: GOOD ( 12.97 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.2 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [216.71.154.253 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: robh@kernel.org, alexandre.belloni@bootlin.com, kamel.bouhara@bootlin.com, wsa@the-dreams.de, linux@armlinux.org.uk, Ludovic.Desroches@microchip.com, Codrin Ciubotariu , peda@axentia.se Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Kamel Bouhara Implement i2c bus recovery when slaves devices might hold SDA low. In this case re-assign SCL/SDA to gpios and issue 9 dummy clock pulses until the slave release SDA. Signed-off-by: Kamel Bouhara Signed-off-by: Codrin Ciubotariu Acked-by: Ludovic Desroches --- Changes in v3: - removed unnecessary condition from info print; - removed unneded declarations; Changes in v2: - called i2c_recover_bus() after an error occurs, if SDA is down; - release gpios if recovery information is incomplete; drivers/i2c/busses/i2c-at91-master.c | 78 ++++++++++++++++++++++++++++ drivers/i2c/busses/i2c-at91.h | 4 ++ 2 files changed, 82 insertions(+) diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c index 7a862e00b475..0aba51a7df32 100644 --- a/drivers/i2c/busses/i2c-at91-master.c +++ b/drivers/i2c/busses/i2c-at91-master.c @@ -18,11 +18,13 @@ #include #include #include +#include #include #include #include #include #include +#include #include #include #include @@ -478,6 +480,7 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) unsigned long time_left; bool has_unre_flag = dev->pdata->has_unre_flag; bool has_alt_cmd = dev->pdata->has_alt_cmd; + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; /* * WARNING: the TXCOMP bit in the Status Register is NOT a clear on @@ -637,6 +640,13 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_THRCLR | AT91_TWI_LOCKCLR); } + + if (rinfo->get_sda && !(rinfo->get_sda(&dev->adapter))) { + dev_dbg(dev->dev, + "SDA is down; clear bus using gpio\n"); + i2c_recover_bus(&dev->adapter); + } + return ret; } @@ -806,6 +816,70 @@ static int at91_twi_configure_dma(struct at91_twi_dev *dev, u32 phy_addr) return ret; } +static void at91_prepare_twi_recovery(struct i2c_adapter *adap) +{ + struct at91_twi_dev *dev = i2c_get_adapdata(adap); + + pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_gpio); +} + +static void at91_unprepare_twi_recovery(struct i2c_adapter *adap) +{ + struct at91_twi_dev *dev = i2c_get_adapdata(adap); + + pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default); +} + +static int at91_init_twi_recovery_info(struct platform_device *pdev, + struct at91_twi_dev *dev) +{ + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; + + dev->pinctrl = devm_pinctrl_get(&pdev->dev); + if (!dev->pinctrl || IS_ERR(dev->pinctrl)) { + dev_info(dev->dev, "can't get pinctrl, bus recovery not supported\n"); + return PTR_ERR(dev->pinctrl); + } + + dev->pinctrl_pins_default = pinctrl_lookup_state(dev->pinctrl, + PINCTRL_STATE_DEFAULT); + dev->pinctrl_pins_gpio = pinctrl_lookup_state(dev->pinctrl, + "gpio"); + rinfo->sda_gpiod = devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN); + if (PTR_ERR(rinfo->sda_gpiod) == -EPROBE_DEFER) + return -EPROBE_DEFER; + + rinfo->scl_gpiod = devm_gpiod_get(&pdev->dev, "scl", + GPIOD_OUT_HIGH_OPEN_DRAIN); + if (PTR_ERR(rinfo->scl_gpiod) == -EPROBE_DEFER) + return -EPROBE_DEFER; + + if (IS_ERR(rinfo->sda_gpiod) || + IS_ERR(rinfo->scl_gpiod) || + IS_ERR(dev->pinctrl_pins_default) || + IS_ERR(dev->pinctrl_pins_gpio)) { + dev_info(&pdev->dev, "recovery information incomplete\n"); + if (!IS_ERR(rinfo->sda_gpiod)) { + gpiod_put(rinfo->sda_gpiod); + rinfo->sda_gpiod = NULL; + } + if (!IS_ERR(rinfo->scl_gpiod)) { + gpiod_put(rinfo->scl_gpiod); + rinfo->scl_gpiod = NULL; + } + return -EINVAL; + } + + dev_info(&pdev->dev, "using scl, sda for recovery\n"); + + rinfo->prepare_recovery = at91_prepare_twi_recovery; + rinfo->unprepare_recovery = at91_unprepare_twi_recovery; + rinfo->recover_bus = i2c_generic_scl_recovery; + dev->adapter.bus_recovery_info = rinfo; + + return 0; +} + int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr, struct at91_twi_dev *dev) { @@ -838,6 +912,10 @@ int at91_twi_probe_master(struct platform_device *pdev, "i2c-analog-filter"); at91_calc_twi_clock(dev); + rc = at91_init_twi_recovery_info(pdev, dev); + if (rc == -EPROBE_DEFER) + return rc; + dev->adapter.algo = &at91_twi_algorithm; dev->adapter.quirks = &at91_twi_quirks; diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h index 977a67bc0f88..f57a6cab96b4 100644 --- a/drivers/i2c/busses/i2c-at91.h +++ b/drivers/i2c/busses/i2c-at91.h @@ -151,6 +151,10 @@ struct at91_twi_dev { u32 fifo_size; struct at91_twi_dma dma; bool slave_detected; + struct i2c_bus_recovery_info rinfo; + struct pinctrl *pinctrl; + struct pinctrl_state *pinctrl_pins_default; + struct pinctrl_state *pinctrl_pins_gpio; #ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL unsigned smr; struct i2c_client *slave;