/* * Driver for the TWSI (i2c) controller found on the Marvell * orion5x and kirkwood SoC families. * * Author: Albert Aribaud <albert.u.boot@aribaud.net> * 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; }