From patchwork Fri Feb 7 16:55:31 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Auchter X-Patchwork-Id: 236052 List-Id: U-Boot discussion From: michael.auchter at ni.com (Michael Auchter) Date: Fri, 7 Feb 2020 10:55:31 -0600 Subject: [PATCH 1/2] dm: i2c-gpio: rework gpio get/set functions In-Reply-To: <20200123223009.213180-1-michael.auchter@ni.com> References: <20200123223009.213180-1-michael.auchter@ni.com> Message-ID: <20200207165532.219139-1-michael.auchter@ni.com> This patch reworks i2c-gpio to make it easier to switch out the implementation of the sda/scl get/set functions. This is in preparation for a patch to conditionally implement clock stretching support. Signed-off-by: Michael Auchter Cc: Heiko Schocher Reviewed-by: Heiko Schocher --- drivers/i2c/i2c-gpio.c | 133 ++++++++++++++++++++--------------------- 1 file changed, 64 insertions(+), 69 deletions(-) diff --git a/drivers/i2c/i2c-gpio.c b/drivers/i2c/i2c-gpio.c index 4e8fa21473..d989449513 100644 --- a/drivers/i2c/i2c-gpio.c +++ b/drivers/i2c/i2c-gpio.c @@ -32,23 +32,32 @@ struct i2c_gpio_bus { int udelay; /* sda, scl */ struct gpio_desc gpios[PIN_COUNT]; + + int (*get_sda)(struct i2c_gpio_bus *bus); + void (*set_sda)(struct i2c_gpio_bus *bus, int bit); + void (*set_scl)(struct i2c_gpio_bus *bus, int bit); }; -static int i2c_gpio_sda_get(struct gpio_desc *sda) +static int i2c_gpio_sda_get(struct i2c_gpio_bus *bus) { + struct gpio_desc *sda = &bus->gpios[PIN_SDA]; + return dm_gpio_get_value(sda); } -static void i2c_gpio_sda_set(struct gpio_desc *sda, int bit) +static void i2c_gpio_sda_set(struct i2c_gpio_bus *bus, int bit) { + struct gpio_desc *sda = &bus->gpios[PIN_SDA]; + if (bit) dm_gpio_set_dir_flags(sda, GPIOD_IS_IN); else dm_gpio_set_dir_flags(sda, GPIOD_IS_OUT); } -static void i2c_gpio_scl_set(struct gpio_desc *scl, int bit) +static void i2c_gpio_scl_set(struct i2c_gpio_bus *bus, int bit) { + struct gpio_desc *scl = &bus->gpios[PIN_SCL]; ulong flags = GPIOD_IS_OUT; if (bit) @@ -56,65 +65,60 @@ static void i2c_gpio_scl_set(struct gpio_desc *scl, int bit) dm_gpio_set_dir_flags(scl, flags); } -static void i2c_gpio_write_bit(struct gpio_desc *scl, struct gpio_desc *sda, - int delay, uchar bit) +static void i2c_gpio_write_bit(struct i2c_gpio_bus *bus, int delay, uchar bit) { - i2c_gpio_scl_set(scl, 0); + bus->set_scl(bus, 0); udelay(delay); - i2c_gpio_sda_set(sda, bit); + bus->set_sda(bus, bit); udelay(delay); - i2c_gpio_scl_set(scl, 1); + bus->set_scl(bus, 1); udelay(2 * delay); } -static int i2c_gpio_read_bit(struct gpio_desc *scl, struct gpio_desc *sda, - int delay) +static int i2c_gpio_read_bit(struct i2c_gpio_bus *bus, int delay) { int value; - i2c_gpio_scl_set(scl, 1); + bus->set_scl(bus, 1); udelay(delay); - value = i2c_gpio_sda_get(sda); + value = bus->get_sda(bus); udelay(delay); - i2c_gpio_scl_set(scl, 0); + bus->set_scl(bus, 0); udelay(2 * delay); return value; } /* START: High -> Low on SDA while SCL is High */ -static void i2c_gpio_send_start(struct gpio_desc *scl, struct gpio_desc *sda, - int delay) +static void i2c_gpio_send_start(struct i2c_gpio_bus *bus, int delay) { udelay(delay); - i2c_gpio_sda_set(sda, 1); + bus->set_sda(bus, 1); udelay(delay); - i2c_gpio_scl_set(scl, 1); + bus->set_scl(bus, 1); udelay(delay); - i2c_gpio_sda_set(sda, 0); + bus->set_sda(bus, 0); udelay(delay); } /* STOP: Low -> High on SDA while SCL is High */ -static void i2c_gpio_send_stop(struct gpio_desc *scl, struct gpio_desc *sda, - int delay) +static void i2c_gpio_send_stop(struct i2c_gpio_bus *bus, int delay) { - i2c_gpio_scl_set(scl, 0); + bus->set_scl(bus, 0); udelay(delay); - i2c_gpio_sda_set(sda, 0); + bus->set_sda(bus, 0); udelay(delay); - i2c_gpio_scl_set(scl, 1); + bus->set_scl(bus, 1); udelay(delay); - i2c_gpio_sda_set(sda, 1); + bus->set_sda(bus, 1); udelay(delay); } /* ack should be I2C_ACK or I2C_NOACK */ -static void i2c_gpio_send_ack(struct gpio_desc *scl, struct gpio_desc *sda, - int delay, int ack) +static void i2c_gpio_send_ack(struct i2c_gpio_bus *bus, int delay, int ack) { - i2c_gpio_write_bit(scl, sda, delay, ack); - i2c_gpio_scl_set(scl, 0); + i2c_gpio_write_bit(bus, delay, ack); + bus->set_scl(bus, 0); udelay(delay); } @@ -123,44 +127,41 @@ static void i2c_gpio_send_ack(struct gpio_desc *scl, struct gpio_desc *sda, * to clock any confused device back into an idle state. Also send a * at the end of the sequence for belts & suspenders. */ -static void i2c_gpio_send_reset(struct gpio_desc *scl, struct gpio_desc *sda, - int delay) +static void i2c_gpio_send_reset(struct i2c_gpio_bus *bus, int delay) { int j; for (j = 0; j < 9; j++) - i2c_gpio_write_bit(scl, sda, delay, 1); + i2c_gpio_write_bit(bus, delay, 1); - i2c_gpio_send_stop(scl, sda, delay); + i2c_gpio_send_stop(bus, delay); } /* Set sda high with low clock, before reading slave data */ -static void i2c_gpio_sda_high(struct gpio_desc *scl, struct gpio_desc *sda, - int delay) +static void i2c_gpio_sda_high(struct i2c_gpio_bus *bus, int delay) { - i2c_gpio_scl_set(scl, 0); + bus->set_scl(bus, 0); udelay(delay); - i2c_gpio_sda_set(sda, 1); + bus->set_sda(bus, 1); udelay(delay); } /* Send 8 bits and look for an acknowledgement */ -static int i2c_gpio_write_byte(struct gpio_desc *scl, struct gpio_desc *sda, - int delay, uchar data) +static int i2c_gpio_write_byte(struct i2c_gpio_bus *bus, int delay, uchar data) { int j; int nack; for (j = 0; j < 8; j++) { - i2c_gpio_write_bit(scl, sda, delay, data & 0x80); + i2c_gpio_write_bit(bus, delay, data & 0x80); data <<= 1; } udelay(delay); /* Look for an (negative logic) and return it */ - i2c_gpio_sda_high(scl, sda, delay); - nack = i2c_gpio_read_bit(scl, sda, delay); + i2c_gpio_sda_high(bus, delay); + nack = i2c_gpio_read_bit(bus, delay); return nack; /* not a nack is an ack */ } @@ -169,31 +170,29 @@ static int i2c_gpio_write_byte(struct gpio_desc *scl, struct gpio_desc *sda, * if ack == I2C_ACK, ACK the byte so can continue reading, else * send I2C_NOACK to end the read. */ -static uchar i2c_gpio_read_byte(struct gpio_desc *scl, struct gpio_desc *sda, - int delay, int ack) +static uchar i2c_gpio_read_byte(struct i2c_gpio_bus *bus, int delay, int ack) { int data; int j; - i2c_gpio_sda_high(scl, sda, delay); + i2c_gpio_sda_high(bus, delay); data = 0; for (j = 0; j < 8; j++) { data <<= 1; - data |= i2c_gpio_read_bit(scl, sda, delay); + data |= i2c_gpio_read_bit(bus, delay); } - i2c_gpio_send_ack(scl, sda, delay, ack); + i2c_gpio_send_ack(bus, delay, ack); return data; } /* send start and the slave chip address */ -int i2c_send_slave_addr(struct gpio_desc *scl, struct gpio_desc *sda, int delay, - uchar chip) +int i2c_send_slave_addr(struct i2c_gpio_bus *bus, int delay, uchar chip) { - i2c_gpio_send_start(scl, sda, delay); + i2c_gpio_send_start(bus, delay); - if (i2c_gpio_write_byte(scl, sda, delay, chip)) { - i2c_gpio_send_stop(scl, sda, delay); + if (i2c_gpio_write_byte(bus, delay, chip)) { + i2c_gpio_send_stop(bus, delay); return -EIO; } @@ -204,29 +203,27 @@ static int i2c_gpio_write_data(struct i2c_gpio_bus *bus, uchar chip, uchar *buffer, int len, bool end_with_repeated_start) { - struct gpio_desc *scl = &bus->gpios[PIN_SCL]; - struct gpio_desc *sda = &bus->gpios[PIN_SDA]; unsigned int delay = bus->udelay; int failures = 0; debug("%s: chip %x buffer %p len %d\n", __func__, chip, buffer, len); - if (i2c_send_slave_addr(scl, sda, delay, chip << 1)) { + if (i2c_send_slave_addr(bus, delay, chip << 1)) { debug("i2c_write, no chip responded %02X\n", chip); return -EIO; } while (len-- > 0) { - if (i2c_gpio_write_byte(scl, sda, delay, *buffer++)) + if (i2c_gpio_write_byte(bus, delay, *buffer++)) failures++; } if (!end_with_repeated_start) { - i2c_gpio_send_stop(scl, sda, delay); + i2c_gpio_send_stop(bus, delay); return failures; } - if (i2c_send_slave_addr(scl, sda, delay, (chip << 1) | 0x1)) { + if (i2c_send_slave_addr(bus, delay, (chip << 1) | 0x1)) { debug("i2c_write, no chip responded %02X\n", chip); return -EIO; } @@ -237,16 +234,14 @@ static int i2c_gpio_write_data(struct i2c_gpio_bus *bus, uchar chip, static int i2c_gpio_read_data(struct i2c_gpio_bus *bus, uchar chip, uchar *buffer, int len) { - struct gpio_desc *scl = &bus->gpios[PIN_SCL]; - struct gpio_desc *sda = &bus->gpios[PIN_SDA]; unsigned int delay = bus->udelay; debug("%s: chip %x buffer: %p len %d\n", __func__, chip, buffer, len); while (len-- > 0) - *buffer++ = i2c_gpio_read_byte(scl, sda, delay, len == 0); + *buffer++ = i2c_gpio_read_byte(bus, delay, len == 0); - i2c_gpio_send_stop(scl, sda, delay); + i2c_gpio_send_stop(bus, delay); return 0; } @@ -277,14 +272,12 @@ static int i2c_gpio_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs) static int i2c_gpio_probe(struct udevice *dev, uint chip, uint chip_flags) { struct i2c_gpio_bus *bus = dev_get_priv(dev); - struct gpio_desc *scl = &bus->gpios[PIN_SCL]; - struct gpio_desc *sda = &bus->gpios[PIN_SDA]; unsigned int delay = bus->udelay; int ret; - i2c_gpio_send_start(scl, sda, delay); - ret = i2c_gpio_write_byte(scl, sda, delay, (chip << 1) | 0); - i2c_gpio_send_stop(scl, sda, delay); + i2c_gpio_send_start(bus, delay); + ret = i2c_gpio_write_byte(bus, delay, (chip << 1) | 0); + i2c_gpio_send_stop(bus, delay); debug("%s: bus: %d (%s) chip: %x flags: %x ret: %d\n", __func__, dev->seq, dev->name, chip, chip_flags, ret); @@ -295,12 +288,10 @@ static int i2c_gpio_probe(struct udevice *dev, uint chip, uint chip_flags) static int i2c_gpio_set_bus_speed(struct udevice *dev, unsigned int speed_hz) { struct i2c_gpio_bus *bus = dev_get_priv(dev); - struct gpio_desc *scl = &bus->gpios[PIN_SCL]; - struct gpio_desc *sda = &bus->gpios[PIN_SDA]; bus->udelay = 1000000 / (speed_hz << 2); - i2c_gpio_send_reset(scl, sda, bus->udelay); + i2c_gpio_send_reset(bus, bus->udelay); return 0; } @@ -320,6 +311,10 @@ static int i2c_gpio_ofdata_to_platdata(struct udevice *dev) bus->udelay = fdtdec_get_int(blob, node, "i2c-gpio,delay-us", DEFAULT_UDELAY); + bus->get_sda = i2c_gpio_sda_get; + bus->set_sda = i2c_gpio_sda_set; + bus->set_scl = i2c_gpio_scl_set; + return 0; error: pr_err("Can't get %s gpios! Error: %d", dev->name, ret); From patchwork Fri Feb 7 16:55:32 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Auchter X-Patchwork-Id: 236051 List-Id: U-Boot discussion From: michael.auchter at ni.com (Michael Auchter) Date: Fri, 7 Feb 2020 10:55:32 -0600 Subject: [PATCH 2/2] dm: i2c-gpio: add support for clock stretching In-Reply-To: <20200207165532.219139-1-michael.auchter@ni.com> References: <20200123223009.213180-1-michael.auchter@ni.com> <20200207165532.219139-1-michael.auchter@ni.com> Message-ID: <20200207165532.219139-2-michael.auchter@ni.com> This adds support for clock stretching to the i2c-gpio driver. This is accomplished by switching the GPIO used for the SCL line to an input when it should be driven high, and polling on the SCL line value until it goes high (indicating that the I2C slave is no longer pulling it low). This is enabled by default; for gpios which cannot be configured as inputs, the i2c-gpio,scl-output-only property can be used to fall back to the previous behavior. Signed-off-by: Michael Auchter Cc: Heiko Schocher Reviewed-by: Heiko Schocher --- doc/device-tree-bindings/i2c/i2c-gpio.txt | 2 ++ drivers/i2c/i2c-gpio.c | 23 ++++++++++++++++++++++- 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/doc/device-tree-bindings/i2c/i2c-gpio.txt b/doc/device-tree-bindings/i2c/i2c-gpio.txt index ba56ed5dea..36910d26a9 100644 --- a/doc/device-tree-bindings/i2c/i2c-gpio.txt +++ b/doc/device-tree-bindings/i2c/i2c-gpio.txt @@ -16,6 +16,8 @@ Optional: The resulting transfer speed can be adjusted by setting the delay[us] between gpio-toggle operations. Speed [Hz] = 1000000 / 4 * udelay[us], It not defined, then default is 5us (~50KHz). +* i2c-gpio,scl-output-only; + Set if SCL is an output only Example: diff --git a/drivers/i2c/i2c-gpio.c b/drivers/i2c/i2c-gpio.c index d989449513..8a8d1ff21b 100644 --- a/drivers/i2c/i2c-gpio.c +++ b/drivers/i2c/i2c-gpio.c @@ -56,6 +56,24 @@ static void i2c_gpio_sda_set(struct i2c_gpio_bus *bus, int bit) } static void i2c_gpio_scl_set(struct i2c_gpio_bus *bus, int bit) +{ + struct gpio_desc *scl = &bus->gpios[PIN_SCL]; + int count = 0; + + if (bit) { + dm_gpio_set_dir_flags(scl, GPIOD_IS_IN); + while (!dm_gpio_get_value(scl) && count++ < 100000) + udelay(1); + + if (!dm_gpio_get_value(scl)) + pr_err("timeout waiting on slave to release scl\n"); + } else { + dm_gpio_set_dir_flags(scl, GPIOD_IS_OUT); + } +} + +/* variant for output only gpios which cannot support clock stretching */ +static void i2c_gpio_scl_set_output_only(struct i2c_gpio_bus *bus, int bit) { struct gpio_desc *scl = &bus->gpios[PIN_SCL]; ulong flags = GPIOD_IS_OUT; @@ -313,7 +331,10 @@ static int i2c_gpio_ofdata_to_platdata(struct udevice *dev) bus->get_sda = i2c_gpio_sda_get; bus->set_sda = i2c_gpio_sda_set; - bus->set_scl = i2c_gpio_scl_set; + if (fdtdec_get_bool(blob, node, "i2c-gpio,scl-output-only")) + bus->set_scl = i2c_gpio_scl_set_output_only; + else + bus->set_scl = i2c_gpio_scl_set; return 0; error: