/****************************************************************************** * The MIT License * * Copyright (c) 2010 Perry Hung. * Copyright (c) 2012 LeafLabs, LLC. * * Permission is hereby granted, free of charge, to any person * obtaining a copy of this software and associated documentation * files (the "Software"), to deal in the Software without * restriction, including without limitation the rights to use, copy, * modify, merge, publish, distribute, sublicense, and/or sell copies * of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be * included in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. *****************************************************************************/ /** * @file libmaple/i2c.c * @author Perry Hung * @brief Inter-Integrated Circuit (I2C) support. * * Currently, only master mode is supported. */ #include #include #include #include #include #include #include static inline int32 wait_for_state_change(i2c_dev *dev, i2c_state state, uint32 timeout); /** * @brief Fill data register with slave address * @param dev I2C device * @param addr Slave address * @param rw Read/write bit */ static inline void i2c_send_slave_addr(i2c_dev *dev, uint32 addr, uint32 rw) { dev->regs->DR = (addr << 1) | rw; } /* * Simple debugging trail. Define I2C_DEBUG to turn on. */ #ifdef I2C_DEBUG #define NR_CRUMBS 128 static struct crumb crumbs[NR_CRUMBS]; static uint32 cur_crumb = 0; static inline void i2c_drop_crumb(uint32 event, uint32 arg0, uint32 arg1) { if (cur_crumb < NR_CRUMBS) { struct crumb *crumb = &crumbs[cur_crumb++]; crumb->event = event; crumb->arg0 = arg0; crumb->arg1 = arg1; } } #define I2C_CRUMB(event, arg0, arg1) i2c_drop_crumb(event, arg0, arg1) #else #define I2C_CRUMB(event, arg0, arg1) #endif struct crumb { uint32 event; uint32 arg0; uint32 arg1; }; enum { IRQ_ENTRY = 1, TXE_ONLY = 2, TXE_BTF = 3, STOP_SENT = 4, TEST = 5, RX_ADDR_START = 6, RX_ADDR_STOP = 7, RXNE_ONLY = 8, RXNE_SENDING = 9, RXNE_START_SENT = 10, RXNE_STOP_SENT = 11, RXNE_DONE = 12, ERROR_ENTRY = 13, }; /** * @brief IRQ handler for I2C master. Handles transmission/reception. * @param dev I2C device */ void _i2c_irq_handler(i2c_dev *dev) { /* WTFs: * - Where is I2C_MSG_10BIT_ADDR handled? */ i2c_msg *msg = dev->msg; uint8 read = msg->flags & I2C_MSG_READ; uint32 sr1 = dev->regs->SR1; uint32 sr2 = dev->regs->SR2; I2C_CRUMB(IRQ_ENTRY, sr1, sr2); /* * Reset timeout counter */ dev->timestamp = systick_uptime(); /* * EV5: Start condition sent */ if (sr1 & I2C_SR1_SB) { msg->xferred = 0; i2c_enable_irq(dev, I2C_IRQ_BUFFER); /* * Master receiver */ if (read) { i2c_enable_ack(dev); } i2c_send_slave_addr(dev, msg->addr, read); sr1 = sr2 = 0; } /* * EV6: Slave address sent */ if (sr1 & I2C_SR1_ADDR) { /* * Special case event EV6_1 for master receiver. * Generate NACK and restart/stop condition after ADDR * is cleared. */ if (read) { if (msg->length == 1) { i2c_disable_ack(dev); if (dev->msgs_left > 1) { i2c_start_condition(dev); I2C_CRUMB(RX_ADDR_START, 0, 0); } else { i2c_stop_condition(dev); I2C_CRUMB(RX_ADDR_STOP, 0, 0); } } } else { /* * Master transmitter: write first byte to fill shift * register. We should get another TXE interrupt * immediately to fill DR again. */ if (msg->length != 1) { i2c_write(dev, msg->data[msg->xferred++]); } } sr1 = sr2 = 0; } /* * EV8: Master transmitter * Transmit buffer empty, but we haven't finished transmitting the last * byte written. */ if ((sr1 & I2C_SR1_TXE) && !(sr1 & I2C_SR1_BTF)) { I2C_CRUMB(TXE_ONLY, 0, 0); if (dev->msgs_left) { i2c_write(dev, msg->data[msg->xferred++]); if (msg->xferred == msg->length) { /* * End of this message. Turn off TXE/RXNE and wait for * BTF to send repeated start or stop condition. */ i2c_disable_irq(dev, I2C_IRQ_BUFFER); dev->msgs_left--; } } else { /* * This should be impossible... */ ASSERT(0); } sr1 = sr2 = 0; } /* * EV8_2: Master transmitter * Last byte sent, program repeated start/stop */ if ((sr1 & I2C_SR1_TXE) && (sr1 & I2C_SR1_BTF)) { I2C_CRUMB(TXE_BTF, 0, 0); if (dev->msgs_left) { I2C_CRUMB(TEST, 0, 0); /* * Repeated start insanity: We can't disable ITEVTEN or else SB * won't interrupt, but if we don't disable ITEVTEN, BTF will * continually interrupt us. What the fuck ST? */ i2c_start_condition(dev); while (!(dev->regs->SR1 & I2C_SR1_SB)) ; dev->msg++; } else { i2c_stop_condition(dev); /* * Turn off event interrupts to keep BTF from firing until * the end of the stop condition. Why on earth they didn't * have a start/stop condition request clear BTF is beyond * me. */ i2c_disable_irq(dev, I2C_IRQ_EVENT); I2C_CRUMB(STOP_SENT, 0, 0); dev->state = I2C_STATE_XFER_DONE; } sr1 = sr2 = 0; } /* * EV7: Master Receiver */ if (sr1 & I2C_SR1_RXNE) { I2C_CRUMB(RXNE_ONLY, 0, 0); msg->data[msg->xferred++] = dev->regs->DR; /* * EV7_1: Second to last byte in the reception? Set NACK and generate * stop/restart condition in time for the last byte. We'll get one more * RXNE interrupt before shutting things down. */ if (msg->xferred == (msg->length - 1)) { i2c_disable_ack(dev); if (dev->msgs_left > 2) { i2c_start_condition(dev); I2C_CRUMB(RXNE_START_SENT, 0, 0); } else { i2c_stop_condition(dev); I2C_CRUMB(RXNE_STOP_SENT, 0, 0); } } else if (msg->xferred == msg->length) { dev->msgs_left--; if (dev->msgs_left == 0) { /* * We're done. */ I2C_CRUMB(RXNE_DONE, 0, 0); dev->state = I2C_STATE_XFER_DONE; } else { dev->msg++; } } } } /** * @brief Interrupt handler for I2C error conditions * @param dev I2C device * @sideeffect Aborts any pending I2C transactions */ void _i2c_irq_error_handler(i2c_dev *dev) { I2C_CRUMB(ERROR_ENTRY, dev->regs->SR1, dev->regs->SR2); dev->error_flags = dev->regs->SR2 & (I2C_SR1_BERR | I2C_SR1_ARLO | I2C_SR1_AF | I2C_SR1_OVR); /* Clear flags */ dev->regs->SR1 = 0; dev->regs->SR2 = 0; i2c_stop_condition(dev); i2c_disable_irq(dev, I2C_IRQ_BUFFER | I2C_IRQ_EVENT | I2C_IRQ_ERROR); dev->state = I2C_STATE_ERROR; } /** * @brief Reset an I2C bus. * * Reset is accomplished by clocking out pulses until any hung slaves * release SDA and SCL, then generating a START condition, then a STOP * condition. * * @param dev I2C device */ void i2c_bus_reset(const i2c_dev *dev) { /* Release both lines */ i2c_master_release_bus(dev); /* * Make sure the bus is free by clocking it until any slaves release the * bus. */ while (!gpio_read_bit(dev->gpio_port, dev->sda_pin)) { /* Wait for any clock stretching to finish */ while (!gpio_read_bit(dev->gpio_port, dev->scl_pin)) ; delay_us(10); /* Pull low */ gpio_write_bit(dev->gpio_port, dev->scl_pin, 0); delay_us(10); /* Release high again */ gpio_write_bit(dev->gpio_port, dev->scl_pin, 1); delay_us(10); } /* Generate start then stop condition */ gpio_write_bit(dev->gpio_port, dev->sda_pin, 0); delay_us(10); gpio_write_bit(dev->gpio_port, dev->scl_pin, 0); delay_us(10); gpio_write_bit(dev->gpio_port, dev->scl_pin, 1); delay_us(10); gpio_write_bit(dev->gpio_port, dev->sda_pin, 1); } /** * @brief Initialize an I2C device and reset its registers to their * default values. * @param dev Device to initialize. */ void i2c_init(i2c_dev *dev) { rcc_reset_dev(dev->clk_id); rcc_clk_enable(dev->clk_id); } /** * @brief Initialize an I2C device as bus master * @param dev Device to enable * @param flags Bitwise or of the following I2C options: * I2C_FAST_MODE: 400 khz operation, * I2C_DUTY_16_9: 16/9 Tlow/Thigh duty cycle (only applicable for * fast mode), * I2C_BUS_RESET: Reset the bus and clock out any hung slaves on * initialization, * I2C_10BIT_ADDRESSING: Enable 10-bit addressing, * I2C_REMAP: Remap I2C1 to SCL/PB8 SDA/PB9. */ void i2c_master_enable(i2c_dev *dev, uint32 flags) { #define I2C_CLK (STM32_PCLK1/1000000) uint32 ccr = 0; uint32 trise = 0; /* PE must be disabled to configure the device */ ASSERT(!(dev->regs->CR1 & I2C_CR1_PE)); if ((dev == I2C1) && (flags & I2C_REMAP)) { afio_remap(AFIO_REMAP_I2C1); I2C1->sda_pin = 9; I2C1->scl_pin = 8; } /* Reset the bus. Clock out any hung slaves. */ if (flags & I2C_BUS_RESET) { i2c_bus_reset(dev); } /* Turn on clock and set GPIO modes */ i2c_init(dev); i2c_config_gpios(dev); /* I2C1 and I2C2 are fed from APB1, clocked at 36MHz */ i2c_set_input_clk(dev, I2C_CLK); if (flags & I2C_FAST_MODE) { ccr |= I2C_CCR_FS; if (flags & I2C_DUTY_16_9) { /* Tlow/Thigh = 16/9 */ ccr |= I2C_CCR_DUTY; ccr |= STM32_PCLK1/(400000 * 25); } else { /* Tlow/Thigh = 2 */ ccr |= STM32_PCLK1/(400000 * 3); } trise = (300 * (I2C_CLK)/1000) + 1; } else { /* Tlow/Thigh = 1 */ ccr = STM32_PCLK1/(100000 * 2); trise = I2C_CLK + 1; } /* Set minimum required value if CCR < 1*/ if ((ccr & I2C_CCR_CCR) == 0) { ccr |= 0x1; } i2c_set_clk_control(dev, ccr); i2c_set_trise(dev, trise); /* Enable event and buffer interrupts */ nvic_irq_enable(dev->ev_nvic_line); nvic_irq_enable(dev->er_nvic_line); i2c_enable_irq(dev, I2C_IRQ_EVENT | I2C_IRQ_BUFFER | I2C_IRQ_ERROR); /* * Important STM32 Errata: * * See STM32F10xx8 and STM32F10xxB Errata sheet (Doc ID 14574 Rev 8), * Section 2.11.1, 2.11.2. * * 2.11.1: * When the EV7, EV7_1, EV6_1, EV6_3, EV2, EV8, and EV3 events are not * managed before the current byte is being transferred, problems may be * encountered such as receiving an extra byte, reading the same data twice * or missing data. * * 2.11.2: * In Master Receiver mode, when closing the communication using * method 2, the content of the last read data can be corrupted. * * If the user software is not able to read the data N-1 before the STOP * condition is generated on the bus, the content of the shift register * (data N) will be corrupted. (data N is shifted 1-bit to the left). * * ---------------------------------------------------------------------- * * In order to ensure that events are not missed, the i2c interrupt must * not be preempted. We set the i2c interrupt priority to be the highest * interrupt in the system (priority level 0). All other interrupts have * been initialized to priority level 16. See nvic_init(). */ nvic_irq_set_priority(dev->ev_nvic_line, 0); nvic_irq_set_priority(dev->er_nvic_line, 0); /* Make it go! */ i2c_peripheral_enable(dev); dev->state = I2C_STATE_IDLE; } /** * @brief Process an i2c transaction. * * Transactions are composed of one or more i2c_msg's, and may be read * or write tranfers. Multiple i2c_msg's will generate a repeated * start in between messages. * * @param dev I2C device * @param msgs Messages to send/receive * @param num Number of messages to send/receive * @param timeout Bus idle timeout in milliseconds before aborting the * transfer. 0 denotes no timeout. * @return 0 on success, * I2C_ERROR_PROTOCOL if there was a protocol error, * I2C_ERROR_TIMEOUT if the transfer timed out. */ int32 i2c_master_xfer(i2c_dev *dev, i2c_msg *msgs, uint16 num, uint32 timeout) { int32 rc; ASSERT(dev->state == I2C_STATE_IDLE); dev->msg = msgs; dev->msgs_left = num; dev->timestamp = systick_uptime(); dev->state = I2C_STATE_BUSY; i2c_enable_irq(dev, I2C_IRQ_EVENT); i2c_start_condition(dev); rc = wait_for_state_change(dev, I2C_STATE_XFER_DONE, timeout); if (rc < 0) { goto out; } dev->state = I2C_STATE_IDLE; out: return rc; } /** * @brief Wait for an I2C event, or time out in case of error. * @param dev I2C device * @param state I2C_state state to wait for * @param timeout Timeout, in milliseconds * @return 0 if target state is reached, a negative value on error. */ static inline int32 wait_for_state_change(i2c_dev *dev, i2c_state state, uint32 timeout) { i2c_state tmp; while (1) { tmp = dev->state; if (tmp == I2C_STATE_ERROR) { return I2C_STATE_ERROR; } if (tmp == state) { return 0; } if (timeout) { if (systick_uptime() > (dev->timestamp + timeout)) { /* TODO: overflow? */ /* TODO: racy? */ return I2C_ERROR_TIMEOUT; } } } }