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Diffstat (limited to 'chip/lm4/i2c.c')
| -rw-r--r-- | chip/lm4/i2c.c | 224 |
1 files changed, 224 insertions, 0 deletions
diff --git a/chip/lm4/i2c.c b/chip/lm4/i2c.c new file mode 100644 index 0000000000..401bfdf6b9 --- /dev/null +++ b/chip/lm4/i2c.c @@ -0,0 +1,224 @@ +/* Copyright (c) 2011 The Chromium OS Authors. All rights reserved. + * Use of this source code is governed by a BSD-style license that can be + * found in the LICENSE file. + */ + +/* Temperature sensor module for Chrome EC */ + +#include "board.h" +#include "console.h" +#include "i2c.h" +#include "timer.h" +#include "registers.h" +#include "uart.h" +#include "util.h" + +/* I2C ports */ +#define I2C_PORT_THERMAL 5 // port 5 / PB6:7 on link, but PG6:7 on badger +#define I2C_PORT_BATTERY 5 // port 0 / PB2:3 on Link, open on badger +#define I2C_PORT_CHARGER 5 // port 1 / PA6:7 on Link, user LED on badger +/* I2C port speed in kbps */ +#define I2C_SPEED_THERMAL 400 /* TODO: TMP007 supports 3.4Mbps + operation; use faster speed? */ +#define I2C_SPEED_BATTERY 100 +#define I2C_SPEED_CHARGER 100 + + +/* Waits for the I2C bus to go idle */ +static int wait_idle(int port) +{ + int s, i; + + /* Spin waiting for busy flag to go away */ + /* TODO: should use interrupt handler */ + for (i = 1000; i >= 0; i--) { + s = LM4_I2C_MCS(port); + if (s & 0x01) { + /* Still busy */ + udelay(1000); + continue; + } + + /* Check for errors */ + if (s & 0x02) + return EC_ERROR_UNKNOWN; + + return EC_SUCCESS; + } + return EC_ERROR_TIMEOUT; +} + + +int i2c_read16(int port, int slave_addr, int offset, int* data) +{ + int rv; + int d; + + *data = 0; + + /* Transmit the offset address to the slave; leave the master in + * transmit state. */ + LM4_I2C_MSA(port) = (slave_addr & 0xff) | 0x00; + LM4_I2C_MDR(port) = offset & 0xff; + LM4_I2C_MCS(port) = 0x03; + + rv = wait_idle(port); + if (rv) + return rv; + + /* Send repeated start followed by receive */ + LM4_I2C_MSA(port) = (slave_addr & 0xff) | 0x01; + LM4_I2C_MCS(port) = 0x0b; + + rv = wait_idle(port); + if (rv) + return rv; + + /* Read the first byte */ + d = LM4_I2C_MDR(port) & 0xff; + + /* Issue another read and then a stop. */ + LM4_I2C_MCS(port) = 0x05; + + rv = wait_idle(port); + if (rv) + return rv; + + /* Read the second byte */ + if (slave_addr & I2C_FLAG_BIG_ENDIAN) + *data = (d << 8) | (LM4_I2C_MDR(port) & 0xff); + else + *data = ((LM4_I2C_MDR(port) & 0xff) << 8) | d; + return EC_SUCCESS; +} + + +int i2c_write16(int port, int slave_addr, int offset, int data) +{ + int rv; + + /* Transmit the offset address to the slave; leave the master in + * transmit state. */ + LM4_I2C_MDR(port) = offset & 0xff; + LM4_I2C_MSA(port) = (slave_addr & 0xff) | 0x00; + LM4_I2C_MCS(port) = 0x03; + + rv = wait_idle(port); + if (rv) + return rv; + + /* Transmit the first byte */ + if (slave_addr & I2C_FLAG_BIG_ENDIAN) + LM4_I2C_MDR(port) = (data >> 8) & 0xff; + else + LM4_I2C_MDR(port) = data & 0xff; + LM4_I2C_MCS(port) = 0x01; + + rv = wait_idle(port); + if (rv) + return rv; + + /* Transmit the second byte and then a stop */ + if (slave_addr & I2C_FLAG_BIG_ENDIAN) + LM4_I2C_MDR(port) = data & 0xff; + else + LM4_I2C_MDR(port) = (data >> 8) & 0xff; + LM4_I2C_MCS(port) = 0x05; + + return wait_idle(port); +} + + +/*****************************************************************************/ +/* Console commands */ + + +static void scan_bus(int port, char *desc) +{ + int rv; + int a; + + uart_printf("Scanning %s I2C bus...\n", desc); + + for (a = 0; a < 0x100; a += 2) { + uart_puts("."); + + /* Do a single read */ + LM4_I2C_MSA(port) = a | 0x01; + LM4_I2C_MCS(port) = 0x07; + rv = wait_idle(port); + if (rv == EC_SUCCESS) + uart_printf("\nFound device at 0x%02x\n", a); + } + uart_puts("\n"); +} + + +static int command_scan(int argc, char **argv) +{ + scan_bus(I2C_PORT_THERMAL, "thermal"); + scan_bus(I2C_PORT_BATTERY, "battery"); + scan_bus(I2C_PORT_CHARGER, "charger"); + uart_puts("done.\n"); + return EC_SUCCESS; +} + + +static const struct console_command console_commands[] = { + {"i2cscan", command_scan}, +}; +static const struct console_group command_group = { + "I2C", console_commands, ARRAY_SIZE(console_commands) +}; + + +/*****************************************************************************/ +/* Initialization */ + +/* Configures GPIOs for the module. */ +static void configure_gpio(void) +{ + volatile uint32_t scratch __attribute__((unused)); + + /* Enable GPIOG module and delay a few clocks */ + LM4_SYSTEM_RCGCGPIO |= 0x0040; + scratch = LM4_SYSTEM_RCGCGPIO; + + /* Use alternate function 3 for PG6:7 */ + LM4_GPIO_AFSEL(G) |= 0xc0; + LM4_GPIO_PCTL(G) = (LM4_GPIO_PCTL(N) & 0x00ffffff) | 0x33000000; + LM4_GPIO_DEN(G) |= 0xc0; + /* Configure SDA as open-drain. SCL should not be open-drain, + * since it has an internal pull-up. */ + LM4_GPIO_ODR(G) |= 0x80; +} + + +int i2c_init(void) +{ + volatile uint32_t scratch __attribute__((unused)); + + /* Enable I2C5 module and delay a few clocks */ + LM4_SYSTEM_RCGCI2C |= (1 << I2C_PORT_THERMAL) | + (1 << I2C_PORT_BATTERY) | (1 << I2C_PORT_CHARGER); + scratch = LM4_SYSTEM_RCGCI2C; + + /* Configure GPIOs */ + configure_gpio(); + + /* Initialize ports as master */ + LM4_I2C_MCR(I2C_PORT_THERMAL) = 0x10; + LM4_I2C_MTPR(I2C_PORT_THERMAL) = + (CPU_CLOCK / (I2C_SPEED_THERMAL * 10 * 2)) - 1; + + LM4_I2C_MCR(I2C_PORT_BATTERY) = 0x10; + LM4_I2C_MTPR(I2C_PORT_BATTERY) = + (CPU_CLOCK / (I2C_SPEED_BATTERY * 10 * 2)) - 1; + + LM4_I2C_MCR(I2C_PORT_CHARGER) = 0x10; + LM4_I2C_MTPR(I2C_PORT_CHARGER) = + (CPU_CLOCK / (I2C_SPEED_CHARGER * 10 * 2)) - 1; + + console_register_commands(&command_group); + return EC_SUCCESS; +} |