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Tue, 25 Feb 2020 08:50:15 -0700 Received: from rob-ult-m19940.microchip.com (10.10.115.15) by chn-vm-ex02.mchp-main.com (10.10.85.144) with Microsoft SMTP Server id 15.1.1713.5 via Frontend Transport; Tue, 25 Feb 2020 08:50:25 -0700 From: Codrin Ciubotariu To: , , , Subject: [PATCH v4 1/4] i2c: at91: Send bus clear command if SDA is down Date: Tue, 25 Feb 2020 17:50:09 +0200 Message-ID: <20200225155012.22764-1-codrin.ciubotariu@microchip.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200225_075031_033076_46ED3269 X-CRM114-Status: GOOD ( 16.55 ) X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.3 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 [216.71.150.166 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches 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: alexandre.belloni@bootlin.com, wsa@the-dreams.de, linux@armlinux.org.uk, ludovic.desroches@microchip.com, robh+dt@kernel.org, Codrin Ciubotariu , peda@axentia.se Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org After a transfer timeout, some faulty I2C slave devices might hold down the SDA pin. We can generate a bus clear command, hoping that the slave might release the pins. If the CLEAR command is not supported, we will use gpio recovery, if available, to reset the bus. Signed-off-by: Codrin Ciubotariu Acked-by: Ludovic Desroches --- Changes in v4: - moved the HW bus clear command in a recover_bus() function, to be able to just call i2c_recover_bus() if a transfer fails; - recovery gpios are no longer taken if HW bus clear command is supported; 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-core.c | 2 ++ drivers/i2c/busses/i2c-at91-master.c | 49 ++++++++++++++++++++++++---- drivers/i2c/busses/i2c-at91.h | 7 +++- 3 files changed, 50 insertions(+), 8 deletions(-) diff --git a/drivers/i2c/busses/i2c-at91-core.c b/drivers/i2c/busses/i2c-at91-core.c index 3da1a8acecb5..e14edd236108 100644 --- a/drivers/i2c/busses/i2c-at91-core.c +++ b/drivers/i2c/busses/i2c-at91-core.c @@ -131,6 +131,7 @@ static struct at91_twi_pdata sama5d2_config = { .has_dig_filtr = true, .has_adv_dig_filtr = true, .has_ana_filtr = true, + .has_clear_cmd = false, /* due to errata, CLEAR cmd is not working */ }; static struct at91_twi_pdata sam9x60_config = { @@ -142,6 +143,7 @@ static struct at91_twi_pdata sam9x60_config = { .has_dig_filtr = true, .has_adv_dig_filtr = true, .has_ana_filtr = true, + .has_clear_cmd = true, }; static const struct of_device_id atmel_twi_dt_ids[] = { diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c index 0aba51a7df32..776e95962ab6 100644 --- a/drivers/i2c/busses/i2c-at91-master.c +++ b/drivers/i2c/busses/i2c-at91-master.c @@ -480,7 +480,6 @@ 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 @@ -641,11 +640,12 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev) 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); - } + /* + * some faulty I2C slave devices might hold SDA down; + * we can send a bus clear command, hoping that the pins will be + * released + */ + i2c_recover_bus(&dev->adapter); return ret; } @@ -830,7 +830,7 @@ static void at91_unprepare_twi_recovery(struct i2c_adapter *adap) pinctrl_select_state(dev->pinctrl, dev->pinctrl_pins_default); } -static int at91_init_twi_recovery_info(struct platform_device *pdev, +static int at91_init_twi_recovery_gpio(struct platform_device *pdev, struct at91_twi_dev *dev) { struct i2c_bus_recovery_info *rinfo = &dev->rinfo; @@ -880,6 +880,41 @@ static int at91_init_twi_recovery_info(struct platform_device *pdev, return 0; } +static int at91_twi_recover_bus_cmd(struct i2c_adapter *adap) +{ + struct at91_twi_dev *dev = i2c_get_adapdata(adap); + + dev->transfer_status |= at91_twi_read(dev, AT91_TWI_SR); + if (!(dev->transfer_status & AT91_TWI_SDA)) { + dev_dbg(dev->dev, "SDA is down; sending bus clear command\n"); + if (dev->use_alt_cmd) { + unsigned int acr; + + acr = at91_twi_read(dev, AT91_TWI_ACR); + acr &= ~AT91_TWI_ACR_DATAL_MASK; + at91_twi_write(dev, AT91_TWI_ACR, acr); + } + at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_CLEAR); + } + + return 0; +} + +static int at91_init_twi_recovery_info(struct platform_device *pdev, + struct at91_twi_dev *dev) +{ + struct i2c_bus_recovery_info *rinfo = &dev->rinfo; + bool has_clear_cmd = dev->pdata->has_clear_cmd; + + if (!has_clear_cmd) + return at91_init_twi_recovery_gpio(pdev, dev); + + rinfo->recover_bus = at91_twi_recover_bus_cmd; + 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) { diff --git a/drivers/i2c/busses/i2c-at91.h b/drivers/i2c/busses/i2c-at91.h index f57a6cab96b4..7e7b4955ca7f 100644 --- a/drivers/i2c/busses/i2c-at91.h +++ b/drivers/i2c/busses/i2c-at91.h @@ -36,6 +36,7 @@ #define AT91_TWI_SVDIS BIT(5) /* Slave Transfer Disable */ #define AT91_TWI_QUICK BIT(6) /* SMBus quick command */ #define AT91_TWI_SWRST BIT(7) /* Software Reset */ +#define AT91_TWI_CLEAR BIT(15) /* Bus clear command */ #define AT91_TWI_ACMEN BIT(16) /* Alternative Command Mode Enable */ #define AT91_TWI_ACMDIS BIT(17) /* Alternative Command Mode Disable */ #define AT91_TWI_THRCLR BIT(24) /* Transmit Holding Register Clear */ @@ -69,6 +70,8 @@ #define AT91_TWI_NACK BIT(8) /* Not Acknowledged */ #define AT91_TWI_EOSACC BIT(11) /* End Of Slave Access */ #define AT91_TWI_LOCK BIT(23) /* TWI Lock due to Frame Errors */ +#define AT91_TWI_SCL BIT(24) /* TWI SCL status */ +#define AT91_TWI_SDA BIT(25) /* TWI SDA status */ #define AT91_TWI_INT_MASK \ (AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY | AT91_TWI_NACK \ @@ -81,7 +84,8 @@ #define AT91_TWI_THR 0x0034 /* Transmit Holding Register */ #define AT91_TWI_ACR 0x0040 /* Alternative Command Register */ -#define AT91_TWI_ACR_DATAL(len) ((len) & 0xff) +#define AT91_TWI_ACR_DATAL_MASK GENMASK(15, 0) +#define AT91_TWI_ACR_DATAL(len) ((len) & AT91_TWI_ACR_DATAL_MASK) #define AT91_TWI_ACR_DIR BIT(8) #define AT91_TWI_FILTR 0x0044 @@ -118,6 +122,7 @@ struct at91_twi_pdata { bool has_dig_filtr; bool has_adv_dig_filtr; bool has_ana_filtr; + bool has_clear_cmd; struct at_dma_slave dma_slave; };