diff options
Diffstat (limited to 'src/soc/intel/common/lpss_i2c.c')
| -rw-r--r-- | src/soc/intel/common/lpss_i2c.c | 379 |
1 files changed, 379 insertions, 0 deletions
diff --git a/src/soc/intel/common/lpss_i2c.c b/src/soc/intel/common/lpss_i2c.c new file mode 100644 index 0000000000..2ac8e667c7 --- /dev/null +++ b/src/soc/intel/common/lpss_i2c.c @@ -0,0 +1,379 @@ +/* + * This file is part of the coreboot project. + * + * Copyright 2009 Vipin Kumar, ST Microelectronics + * Copyright 2016 Google Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; version 2 of the License. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#include <arch/io.h> +#include <commonlib/helpers.h> +#include <console/console.h> +#include <device/device.h> +#include <device/i2c.h> +#include <timer.h> +#include "lpss_i2c.h" + +struct lpss_i2c_regs { + uint32_t control; + uint32_t target_addr; + uint32_t slave_addr; + uint32_t master_addr; + uint32_t cmd_data; + uint32_t ss_scl_hcnt; + uint32_t ss_scl_lcnt; + uint32_t fs_scl_hcnt; + uint32_t fs_scl_lcnt; + uint32_t hs_scl_hcnt; + uint32_t hs_scl_lcnt; + uint32_t intr_stat; + uint32_t intr_mask; + uint32_t raw_intr_stat; + uint32_t rx_thresh; + uint32_t tx_thresh; + uint32_t clear_intr; + uint32_t clear_rx_under_intr; + uint32_t clear_rx_over_intr; + uint32_t clear_tx_over_intr; + uint32_t clear_rd_req_intr; + uint32_t clear_tx_abrt_intr; + uint32_t clear_rx_done_intr; + uint32_t clear_activity_intr; + uint32_t clear_stop_det_intr; + uint32_t clear_start_det_intr; + uint32_t clear_gen_call_intr; + uint32_t enable; + uint32_t status; + uint32_t tx_level; + uint32_t rx_level; + uint32_t sda_hold; + uint32_t tx_abort_source; +} __attribute__((packed)); + +/* Use a ~2ms timeout for various operations */ +#define LPSS_I2C_TIMEOUT_US 2000 + +/* High and low times in different speed modes (in ns) */ +enum { + /* Standard Speed */ + MIN_SS_SCL_HIGHTIME = 4000, + MIN_SS_SCL_LOWTIME = 4700, + /* Fast/Fast+ Speed */ + MIN_FS_SCL_HIGHTIME = 600, + MIN_FS_SCL_LOWTIME = 1300, + /* High Speed */ + MIN_HS_SCL_HIGHTIME = 60, + MIN_HS_SCL_LOWTIME = 160, +}; + +/* Control register definitions */ +enum { + CONTROL_MASTER_MODE = (1 << 0), + CONTROL_SPEED_SS = (1 << 1), + CONTROL_SPEED_FS = (1 << 2), + CONTROL_SPEED_HS = (3 << 1), + CONTROL_SPEED_MASK = (3 << 1), + CONTROL_10BIT_SLAVE = (1 << 3), + CONTROL_10BIT_MASTER = (1 << 4), + CONTROL_RESTART_ENABLE = (1 << 5), + CONTROL_SLAVE_DISABLE = (1 << 6), +}; + +/* Command/Data register definitions */ +enum { + CMD_DATA_CMD = (1 << 8), + CMD_DATA_STOP = (1 << 9), +}; + +/* Status register definitions */ +enum { + STATUS_ACTIVITY = (1 << 0), + STATUS_TX_FIFO_NOT_FULL = (1 << 1), + STATUS_TX_FIFO_EMPTY = (1 << 2), + STATUS_RX_FIFO_NOT_EMPTY = (1 << 3), + STATUS_RX_FIFO_FULL = (1 << 4), + STATUS_MASTER_ACTIVITY = (1 << 5), + STATUS_SLAVE_ACTIVITY = (1 << 6), +}; + +/* Enable register definitions */ +enum { + ENABLE_CONTROLLER = (1 << 0), +}; + +/* Interrupt status register definitions */ +enum { + INTR_STAT_RX_UNDER = (1 << 0), + INTR_STAT_RX_OVER = (1 << 1), + INTR_STAT_RX_FULL = (1 << 2), + INTR_STAT_TX_OVER = (1 << 3), + INTR_STAT_TX_EMPTY = (1 << 4), + INTR_STAT_RD_REQ = (1 << 5), + INTR_STAT_TX_ABORT = (1 << 6), + INTR_STAT_RX_DONE = (1 << 7), + INTR_STAT_ACTIVITY = (1 << 8), + INTR_STAT_STOP_DET = (1 << 9), + INTR_STAT_START_DET = (1 << 10), + INTR_STAT_GEN_CALL = (1 << 11), +}; + +/* Enable this I2C controller */ +static void lpss_i2c_enable(struct lpss_i2c_regs *regs) +{ + uint32_t enable = read32(®s->enable); + + if (!(enable & ENABLE_CONTROLLER)) + write32(®s->enable, enable | ENABLE_CONTROLLER); +} + +/* Disable this I2C controller */ +static int lpss_i2c_disable(struct lpss_i2c_regs *regs) +{ + uint32_t enable = read32(®s->enable); + + if (enable & ENABLE_CONTROLLER) { + struct stopwatch sw; + + write32(®s->enable, enable & ~ENABLE_CONTROLLER); + + /* Wait for enable bit to clear */ + stopwatch_init_usecs_expire(&sw, LPSS_I2C_TIMEOUT_US); + while (read32(®s->enable) & ENABLE_CONTROLLER) + if (stopwatch_expired(&sw)) + return -1; + } + + return 0; +} + +/* Wait for this I2C controller to go idle for transmit */ +static int lpss_i2c_wait_for_bus_idle(struct lpss_i2c_regs *regs) +{ + struct stopwatch sw; + + /* Start timeout for up to 16 bytes in FIFO */ + stopwatch_init_usecs_expire(&sw, 16 * LPSS_I2C_TIMEOUT_US); + + while (!stopwatch_expired(&sw)) { + uint32_t status = read32(®s->status); + + /* Check for master activity and keep waiting */ + if (status & STATUS_MASTER_ACTIVITY) + continue; + + /* Check for TX FIFO empty to indicate TX idle */ + if (status & STATUS_TX_FIFO_EMPTY) + return 0; + } + + /* Timed out while waiting for bus to go idle */ + return -1; +} + +/* Transfer one byte of one segment, sending stop bit if requested */ +static int lpss_i2c_transfer_byte(struct lpss_i2c_regs *regs, + struct i2c_seg *segment, + size_t byte, int send_stop) +{ + struct stopwatch sw; + uint32_t cmd = CMD_DATA_CMD; /* Read op */ + + stopwatch_init_usecs_expire(&sw, LPSS_I2C_TIMEOUT_US); + + if (!segment->read) { + /* Write op only: Wait for FIFO not full */ + while (!(read32(®s->status) & STATUS_TX_FIFO_NOT_FULL)) { + if (stopwatch_expired(&sw)) { + printk(BIOS_ERR, "I2C transmit timeout\n"); + return -1; + } + } + cmd = segment->buf[byte]; + } + + /* Send stop on last byte, if desired */ + if (send_stop && byte == segment->len - 1) + cmd |= CMD_DATA_STOP; + + write32(®s->cmd_data, cmd); + + if (segment->read) { + /* Read op only: Wait for FIFO data and store it */ + while (!(read32(®s->status) & STATUS_RX_FIFO_NOT_EMPTY)) { + if (stopwatch_expired(&sw)) { + printk(BIOS_ERR, "I2C receive timeout\n"); + return -1; + } + } + segment->buf[byte] = read32(®s->cmd_data); + } + + return 0; +} + +/* Global I2C bus handler, defined in include/i2c.h */ +int platform_i2c_transfer(unsigned bus, struct i2c_seg *segments, int count) +{ + struct stopwatch sw; + struct lpss_i2c_regs *regs; + size_t byte; + + if (count <= 0 || !segments) + return -1; + + regs = (struct lpss_i2c_regs *)lpss_i2c_base_address(bus); + if (!regs) { + printk(BIOS_ERR, "I2C bus %u base address not found\n", bus); + return -1; + } + + if (!(read32(®s->enable) & ENABLE_CONTROLLER)) { + printk(BIOS_ERR, "I2C bus %u not initialized\n", bus); + return -1; + } + + if (lpss_i2c_wait_for_bus_idle(regs)) { + printk(BIOS_ERR, "I2C timeout waiting for bus %u idle\n", bus); + return -1; + } + + /* Process each segment */ + while (count--) { + /* Set target slave address */ + write32(®s->target_addr, segments->chip); + + /* Read or write each byte in segment */ + for (byte = 0; byte < segments->len; byte++) { + /* + * Set stop condition on final segment only. + * Repeated start will be automatically generated + * by the controller on R->W or W->R switch. + */ + if (lpss_i2c_transfer_byte(regs, segments, byte, + count == 0) < 0) { + printk(BIOS_ERR, "I2C %s failed: bus %u " + "addr 0x%02x\n", segments->read ? + "read" : "write", bus, segments->chip); + return -1; + } + } + segments++; + } + + /* Wait for interrupt status to indicate transfer is complete */ + stopwatch_init_usecs_expire(&sw, LPSS_I2C_TIMEOUT_US); + while (!(read32(®s->raw_intr_stat) & INTR_STAT_STOP_DET)) { + if (stopwatch_expired(&sw)) { + printk(BIOS_ERR, "I2C stop bit not received\n"); + return -1; + } + } + + /* Read to clear INTR_STAT_STOP_DET */ + read32(®s->clear_stop_det_intr); + + /* Wait for the bus to go idle */ + if (lpss_i2c_wait_for_bus_idle(regs)) { + printk(BIOS_ERR, "I2C timeout waiting for bus %u idle\n", bus); + return -1; + } + + /* Flush the RX FIFO in case it is not empty */ + stopwatch_init_usecs_expire(&sw, 16 * LPSS_I2C_TIMEOUT_US); + while (read32(®s->status) & STATUS_RX_FIFO_NOT_EMPTY) { + if (stopwatch_expired(&sw)) { + printk(BIOS_ERR, "I2C timeout flushing RX FIFO\n"); + return -1; + } + read32(®s->cmd_data); + } + + return 0; +} + +static void lpss_i2c_set_speed(struct lpss_i2c_regs *regs, enum i2c_speed speed) +{ + const int ic_clk = CONFIG_SOC_INTEL_COMMON_LPSS_I2C_CLOCK_MHZ; + uint32_t control, hcnt_min, lcnt_min; + void *hcnt_reg, *lcnt_reg; + + /* Clock must be provided by Kconfig */ + if (!ic_clk || !speed) + return; + + control = read32(®s->control); + control &= ~CONTROL_SPEED_MASK; + + if (speed >= I2C_SPEED_HIGH) { + /* High Speed */ + control |= CONTROL_SPEED_HS; + hcnt_reg = ®s->hs_scl_hcnt; + lcnt_reg = ®s->hs_scl_lcnt; + hcnt_min = MIN_HS_SCL_HIGHTIME; + lcnt_min = MIN_HS_SCL_LOWTIME; + } else if (speed >= I2C_SPEED_FAST) { + /* Fast Speed */ + control |= CONTROL_SPEED_FS; + hcnt_reg = ®s->fs_scl_hcnt; + lcnt_reg = ®s->fs_scl_lcnt; + hcnt_min = MIN_FS_SCL_HIGHTIME; + lcnt_min = MIN_FS_SCL_LOWTIME; + } else { + /* Standard Speed */ + control |= CONTROL_SPEED_SS; + hcnt_reg = ®s->ss_scl_hcnt; + lcnt_reg = ®s->ss_scl_lcnt; + hcnt_min = MIN_SS_SCL_HIGHTIME; + lcnt_min = MIN_SS_SCL_LOWTIME; + } + + /* Select this speed in the control register */ + write32(®s->control, control); + + /* SCL count must be set after the speed is selected */ + write32(hcnt_reg, ic_clk * hcnt_min / KHz); + write32(lcnt_reg, ic_clk * lcnt_min / KHz); +} + +void lpss_i2c_init(unsigned bus, enum i2c_speed speed) +{ + struct lpss_i2c_regs *regs; + + regs = (struct lpss_i2c_regs *)lpss_i2c_base_address(bus); + if (!regs) { + printk(BIOS_ERR, "I2C bus %u base address not found\n", bus); + return; + } + + if (lpss_i2c_disable(regs) < 0) { + printk(BIOS_ERR, "I2C timeout disabling bus %u\n", bus); + return; + } + + /* Put controller in master mode with restart enabled */ + write32(®s->control, CONTROL_MASTER_MODE | CONTROL_SLAVE_DISABLE | + CONTROL_RESTART_ENABLE); + + /* Set bus speed to FAST by default */ + lpss_i2c_set_speed(regs, speed ? : I2C_SPEED_FAST); + + /* Set RX/TX thresholds to smallest values */ + write32(®s->rx_thresh, 0); + write32(®s->tx_thresh, 0); + + /* Enable stop detection interrupt */ + write32(®s->intr_mask, INTR_STAT_STOP_DET); + + lpss_i2c_enable(regs); + + printk(BIOS_INFO, "LPSS I2C bus %u at 0x%p (%u KHz)\n", + bus, regs, (speed ? : I2C_SPEED_FAST) / KHz); +} |