From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH v2 2/6] i2c: at91: implement i2c bus recovery Date: Fri, 3 Jan 2020 09:49:07 +0000 Message-ID: <20200103094821.13185-3-codrin.ciubotariu@microchip.com> References: <20200103094821.13185-1-codrin.ciubotariu@microchip.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20200103094821.13185-1-codrin.ciubotariu@microchip.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: linux-i2c@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Cc: kamel.bouhara@bootlin.com, wsa@the-dreams.de, Nicolas.Ferre@microchip.com, alexandre.belloni@bootlin.com, Ludovic.Desroches@microchip.com, robh@kernel.org, Codrin.Ciubotariu@microchip.com List-Id: linux-i2c@vger.kernel.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 [codrin.ciubotariu@microchip.com: release gpios on error; move i2c_recover_= bus] Signed-off-by: Codrin Ciubotariu --- 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 | 79 ++++++++++++++++++++++++++++ drivers/i2c/busses/i2c-at91.h | 8 +++ 2 files changed, 87 insertions(+) diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-= at91-master.c index 7a862e00b475..c55e8ff35201 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 *de= v) unsigned long time_left; bool has_unre_flag =3D dev->pdata->has_unre_flag; bool has_alt_cmd =3D dev->pdata->has_alt_cmd; + struct i2c_bus_recovery_info *rinfo =3D &dev->rinfo; =20 /* * 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 *d= ev) 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; } =20 @@ -806,6 +816,71 @@ static int at91_twi_configure_dma(struct at91_twi_dev = *dev, u32 phy_addr) return ret; } =20 +static void at91_prepare_twi_recovery(struct i2c_adapter *adap) +{ + struct at91_twi_dev *dev =3D 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 =3D 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 =3D &dev->rinfo; + + dev->pinctrl =3D 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 =3D pinctrl_lookup_state(dev->pinctrl, + PINCTRL_STATE_DEFAULT); + dev->pinctrl_pins_gpio =3D pinctrl_lookup_state(dev->pinctrl, + "gpio"); + rinfo->sda_gpiod =3D devm_gpiod_get(&pdev->dev, "sda", GPIOD_IN); + if (PTR_ERR(rinfo->sda_gpiod) =3D=3D -EPROBE_DEFER) + return -EPROBE_DEFER; + + rinfo->scl_gpiod =3D devm_gpiod_get(&pdev->dev, "scl", + GPIOD_OUT_HIGH_OPEN_DRAIN); + if (PTR_ERR(rinfo->scl_gpiod) =3D=3D -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 =3D NULL; + } + if (!IS_ERR(rinfo->scl_gpiod)) { + gpiod_put(rinfo->scl_gpiod); + rinfo->scl_gpiod =3D NULL; + } + return -EINVAL; + } + + dev_info(&pdev->dev, "using scl%s for recovery\n", + rinfo->sda_gpiod ? ",sda" : ""); + + rinfo->prepare_recovery =3D at91_prepare_twi_recovery; + rinfo->unprepare_recovery =3D at91_unprepare_twi_recovery; + rinfo->recover_bus =3D i2c_generic_scl_recovery; + dev->adapter.bus_recovery_info =3D rinfo; + + return 0; +} + int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr, struct at91_twi_dev *dev) { @@ -838,6 +913,10 @@ int at91_twi_probe_master(struct platform_device *pdev= , "i2c-analog-filter"); at91_calc_twi_clock(dev); =20 + rc =3D at91_init_twi_recovery_info(pdev, dev); + if (rc =3D=3D -EPROBE_DEFER) + return rc; + dev->adapter.algo =3D &at91_twi_algorithm; dev->adapter.quirks =3D &at91_twi_quirks; =20 diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h index 977a67bc0f88..eb335b71e775 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; @@ -171,6 +175,10 @@ void at91_init_twi_bus_master(struct at91_twi_dev *dev= ); int at91_twi_probe_master(struct platform_device *pdev, u32 phy_addr, struct at91_twi_dev *dev); =20 +void at91_twi_prepare_recovery(struct i2c_adapter *adap); +void at91_twi_unprepare_recovery(struct i2c_adapter *adap); +void at91_twi_init_recovery_info(struct at91_twi_dev *dev); + #ifdef CONFIG_I2C_AT91_SLAVE_EXPERIMENTAL void at91_init_twi_bus_slave(struct at91_twi_dev *dev); int at91_twi_probe_slave(struct platform_device *pdev, u32 phy_addr, --=20 2.20.1