diff options
Diffstat (limited to 'u-boot/drivers/i2c/mvtwsi.c')
| -rw-r--r-- | u-boot/drivers/i2c/mvtwsi.c | 428 |
1 files changed, 428 insertions, 0 deletions
diff --git a/u-boot/drivers/i2c/mvtwsi.c b/u-boot/drivers/i2c/mvtwsi.c new file mode 100644 index 0000000..16a536f --- /dev/null +++ b/u-boot/drivers/i2c/mvtwsi.c @@ -0,0 +1,428 @@ +/* + * Driver for the TWSI (i2c) controller found on the Marvell + * orion5x and kirkwood SoC families. + * + * Author: Albert Aribaud <albert.aribaud@free.fr> + * Copyright (c) 2010 Albert Aribaud. + * + * See file CREDITS for list of people who contributed to this + * project. + * + * 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; either version 2 of + * the License, or (at your option) any later version. + * + * 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. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, + * MA 02110-1301 USA + */ + +#include <common.h> +#include <i2c.h> +#include <asm/errno.h> +#include <asm/io.h> + +/* + * include a file that will provide CONFIG_I2C_MVTWSI_BASE + * and possibly other settings + */ + +#if defined(CONFIG_ORION5X) +#include <asm/arch/orion5x.h> +#elif defined(CONFIG_KIRKWOOD) +#include <asm/arch/kirkwood.h> +#else +#error Driver mvtwsi not supported by SoC or board +#endif + +/* + * TWSI register structure + */ + +struct mvtwsi_registers { + u32 slave_address; + u32 data; + u32 control; + union { + u32 status; /* when reading */ + u32 baudrate; /* when writing */ + }; + u32 xtnd_slave_addr; + u32 reserved[2]; + u32 soft_reset; +}; + +/* + * Control register fields + */ + +#define MVTWSI_CONTROL_ACK 0x00000004 +#define MVTWSI_CONTROL_IFLG 0x00000008 +#define MVTWSI_CONTROL_STOP 0x00000010 +#define MVTWSI_CONTROL_START 0x00000020 +#define MVTWSI_CONTROL_TWSIEN 0x00000040 +#define MVTWSI_CONTROL_INTEN 0x00000080 + +/* + * Status register values -- only those expected in normal master + * operation on non-10-bit-address devices; whatever status we don't + * expect in nominal conditions (bus errors, arbitration losses, + * missing ACKs...) we just pass back to the caller as an error + * code. + */ + +#define MVTWSI_STATUS_START 0x08 +#define MVTWSI_STATUS_REPEATED_START 0x10 +#define MVTWSI_STATUS_ADDR_W_ACK 0x18 +#define MVTWSI_STATUS_DATA_W_ACK 0x28 +#define MVTWSI_STATUS_ADDR_R_ACK 0x40 +#define MVTWSI_STATUS_ADDR_R_NAK 0x48 +#define MVTWSI_STATUS_DATA_R_ACK 0x50 +#define MVTWSI_STATUS_DATA_R_NAK 0x58 +#define MVTWSI_STATUS_IDLE 0xF8 + +/* + * The single instance of the controller we'll be dealing with + */ + +static struct mvtwsi_registers *twsi = + (struct mvtwsi_registers *) CONFIG_I2C_MVTWSI_BASE; + +/* + * Returned statuses are 0 for success and nonzero otherwise. + * Currently, cmd_i2c and cmd_eeprom do not interpret an error status. + * Thus to ease debugging, the return status contains some debug info: + * - bits 31..24 are error class: 1 is timeout, 2 is 'status mismatch'. + * - bits 23..16 are the last value of the control register. + * - bits 15..8 are the last value of the status register. + * - bits 7..0 are the expected value of the status register. + */ + +#define MVTWSI_ERROR_WRONG_STATUS 0x01 +#define MVTWSI_ERROR_TIMEOUT 0x02 + +#define MVTWSI_ERROR(ec, lc, ls, es) (((ec << 24) & 0xFF000000) | \ + ((lc << 16) & 0x00FF0000) | ((ls<<8) & 0x0000FF00) | (es & 0xFF)) + +/* + * Wait for IFLG to raise, or return 'timeout'; then if status is as expected, + * return 0 (ok) or return 'wrong status'. + */ +static int twsi_wait(int expected_status) +{ + int control, status; + int timeout = 1000; + + do { + control = readl(&twsi->control); + if (control & MVTWSI_CONTROL_IFLG) { + status = readl(&twsi->status); + if (status == expected_status) + return 0; + else + return MVTWSI_ERROR( + MVTWSI_ERROR_WRONG_STATUS, + control, status, expected_status); + } + udelay(10); /* one clock cycle at 100 kHz */ + } while (timeout--); + status = readl(&twsi->status); + return MVTWSI_ERROR( + MVTWSI_ERROR_TIMEOUT, control, status, expected_status); +} + +/* + * These flags are ORed to any write to the control register + * They allow global setting of TWSIEN and ACK. + * By default none are set. + * twsi_start() sets TWSIEN (in case the controller was disabled) + * twsi_recv() sets ACK or resets it depending on expected status. + */ +static u8 twsi_control_flags = MVTWSI_CONTROL_TWSIEN; + +/* + * Assert the START condition, either in a single I2C transaction + * or inside back-to-back ones (repeated starts). + */ +static int twsi_start(int expected_status) +{ + /* globally set TWSIEN in case it was not */ + twsi_control_flags |= MVTWSI_CONTROL_TWSIEN; + /* assert START */ + writel(twsi_control_flags | MVTWSI_CONTROL_START, &twsi->control); + /* wait for controller to process START */ + return twsi_wait(expected_status); +} + +/* + * Send a byte (i2c address or data). + */ +static int twsi_send(u8 byte, int expected_status) +{ + /* put byte in data register for sending */ + writel(byte, &twsi->data); + /* clear any pending interrupt -- that'll cause sending */ + writel(twsi_control_flags, &twsi->control); + /* wait for controller to receive byte and check ACK */ + return twsi_wait(expected_status); +} + +/* + * Receive a byte. + * Global mvtwsi_control_flags variable says if we should ack or nak. + */ +static int twsi_recv(u8 *byte) +{ + int expected_status, status; + + /* compute expected status based on ACK bit in global control flags */ + if (twsi_control_flags & MVTWSI_CONTROL_ACK) + expected_status = MVTWSI_STATUS_DATA_R_ACK; + else + expected_status = MVTWSI_STATUS_DATA_R_NAK; + /* acknowledge *previous state* and launch receive */ + writel(twsi_control_flags, &twsi->control); + /* wait for controller to receive byte and assert ACK or NAK */ + status = twsi_wait(expected_status); + /* if we did receive expected byte then store it */ + if (status == 0) + *byte = readl(&twsi->data); + /* return status */ + return status; +} + +/* + * Assert the STOP condition. + * This is also used to force the bus back in idle (SDA=SCL=1). + */ +static int twsi_stop(int status) +{ + int control, stop_status; + int timeout = 1000; + + /* assert STOP */ + control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP; + writel(control, &twsi->control); + /* wait for IDLE; IFLG won't rise so twsi_wait() is no use. */ + do { + stop_status = readl(&twsi->status); + if (stop_status == MVTWSI_STATUS_IDLE) + break; + udelay(10); /* one clock cycle at 100 kHz */ + } while (timeout--); + control = readl(&twsi->control); + if (stop_status != MVTWSI_STATUS_IDLE) + if (status == 0) + status = MVTWSI_ERROR( + MVTWSI_ERROR_TIMEOUT, + control, status, MVTWSI_STATUS_IDLE); + return status; +} + +/* + * Ugly formula to convert m and n values to a frequency comes from + * TWSI specifications + */ + +#define TWSI_FREQUENCY(m, n) \ + ((u8) (CONFIG_SYS_TCLK / (10 * (m + 1) * 2 * (1 << n)))) + +/* + * These are required to be reprogrammed before enabling the controller + * because a reset loses them. + * Default values come from the spec, but a twsi_reset will change them. + * twsi_slave_address left uninitialized lest checkpatch.pl complains. + */ + +/* Baudrate generator: m (bits 7..4) =4, n (bits 3..0) =4 */ +static u8 twsi_baud_rate = 0x44; /* baudrate at controller reset */ +/* Default frequency corresponding to default m=4, n=4 */ +static u8 twsi_actual_speed = TWSI_FREQUENCY(4, 4); +/* Default slave address is 0 (so is an uninitialized static) */ +static u8 twsi_slave_address; + +/* + * Reset controller. + * Called at end of i2c_init unsuccessful i2c transactions. + * Controller reset also resets the baud rate and slave address, so + * re-establish them. + */ +static void twsi_reset(void) +{ + /* ensure controller will be enabled by any twsi*() function */ + twsi_control_flags = MVTWSI_CONTROL_TWSIEN; + /* reset controller */ + writel(0, &twsi->soft_reset); + /* wait 2 ms -- this is what the Marvell LSP does */ + udelay(20000); + /* set baud rate */ + writel(twsi_baud_rate, &twsi->baudrate); + /* set slave address even though we don't use it */ + writel(twsi_slave_address, &twsi->slave_address); + writel(0, &twsi->xtnd_slave_addr); + /* assert STOP but don't care for the result */ + (void) twsi_stop(0); +} + +/* + * I2C init called by cmd_i2c when doing 'i2c reset'. + * Sets baud to the highest possible value not exceeding requested one. + */ +void i2c_init(int requested_speed, int slaveadd) +{ + int tmp_speed, highest_speed, n, m; + int baud = 0x44; /* baudrate at controller reset */ + + /* use actual speed to collect progressively higher values */ + highest_speed = 0; + /* compute m, n setting for highest speed not above requested speed */ + for (n = 0; n < 8; n++) { + for (m = 0; m < 16; m++) { + tmp_speed = TWSI_FREQUENCY(m, n); + if ((tmp_speed <= requested_speed) + && (tmp_speed > highest_speed)) { + highest_speed = tmp_speed; + baud = (m << 3) | n; + } + } + } + /* save baud rate and slave for later calls to twsi_reset */ + twsi_baud_rate = baud; + twsi_actual_speed = highest_speed; + twsi_slave_address = slaveadd; + /* reset controller */ + twsi_reset(); +} + +/* + * Begin I2C transaction with expected start status, at given address. + * Common to i2c_probe, i2c_read and i2c_write. + * Expected address status will derive from direction bit (bit 0) in addr. + */ +static int i2c_begin(int expected_start_status, u8 addr) +{ + int status, expected_addr_status; + + /* compute expected address status from direction bit in addr */ + if (addr & 1) /* reading */ + expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK; + else /* writing */ + expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK; + /* assert START */ + status = twsi_start(expected_start_status); + /* send out the address if the start went well */ + if (status == 0) + status = twsi_send(addr, expected_addr_status); + /* return ok or status of first failure to caller */ + return status; +} + +/* + * I2C probe called by cmd_i2c when doing 'i2c probe'. + * Begin read, nak data byte, end. + */ +int i2c_probe(uchar chip) +{ + u8 dummy_byte; + int status; + + /* begin i2c read */ + status = i2c_begin(MVTWSI_STATUS_START, (chip << 1) | 1); + /* dummy read was accepted: receive byte but NAK it. */ + if (status == 0) + status = twsi_recv(&dummy_byte); + /* Stop transaction */ + twsi_stop(0); + /* return 0 or status of first failure */ + return status; +} + +/* + * I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c + * Begin write, send address byte(s), begin read, receive data bytes, end. + * + * NOTE: some EEPROMS want a stop right before the second start, while + * some will choke if it is there. Deciding which we should do is eeprom + * stuff, not i2c, but at the moment the APIs won't let us put it in + * cmd_eeprom, so we have to choose here, and for the moment that'll be + * a repeated start without a preceding stop. + */ +int i2c_read(u8 dev, uint addr, int alen, u8 *data, int length) +{ + int status; + + /* begin i2c write to send the address bytes */ + status = i2c_begin(MVTWSI_STATUS_START, (dev << 1)); + /* send addr bytes */ + while ((status == 0) && alen--) + status = twsi_send(addr >> (8*alen), + MVTWSI_STATUS_DATA_W_ACK); + /* begin i2c read to receive eeprom data bytes */ + if (status == 0) + status = i2c_begin( + MVTWSI_STATUS_REPEATED_START, (dev << 1) | 1); + /* prepare ACK if at least one byte must be received */ + if (length > 0) + twsi_control_flags |= MVTWSI_CONTROL_ACK; + /* now receive actual bytes */ + while ((status == 0) && length--) { + /* reset NAK if we if no more to read now */ + if (length == 0) + twsi_control_flags &= ~MVTWSI_CONTROL_ACK; + /* read current byte */ + status = twsi_recv(data++); + } + /* Stop transaction */ + status = twsi_stop(status); + /* return 0 or status of first failure */ + return status; +} + +/* + * I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c + * Begin write, send address byte(s), send data bytes, end. + */ +int i2c_write(u8 dev, uint addr, int alen, u8 *data, int length) +{ + int status; + + /* begin i2c write to send the eeprom adress bytes then data bytes */ + status = i2c_begin(MVTWSI_STATUS_START, (dev << 1)); + /* send addr bytes */ + while ((status == 0) && alen--) + status = twsi_send(addr >> (8*alen), + MVTWSI_STATUS_DATA_W_ACK); + /* send data bytes */ + while ((status == 0) && (length-- > 0)) + status = twsi_send(*(data++), MVTWSI_STATUS_DATA_W_ACK); + /* Stop transaction */ + status = twsi_stop(status); + /* return 0 or status of first failure */ + return status; +} + +/* + * Bus set routine: we only support bus 0. + */ +int i2c_set_bus_num(unsigned int bus) +{ + if (bus > 0) { + return -1; + } + return 0; +} + +/* + * Bus get routine: hard-return bus 0. + */ +unsigned int i2c_get_bus_num(void) +{ + return 0; +} |