[U-Boot] [PATCH V3 3/4] i2c: rewrite mvtwsi, support orion5x and kirkwood

Prafulla Wadaskar
2010-08-27T12:34:03Z

> -----Original Message-----
> From: u-boot-bounces at lists.denx.de
> [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Albert Aribaud
> Sent: Friday, August 27, 2010 11:42 AM
> To: u-boot at lists.denx.de
> Subject: [U-Boot] [PATCH V3 3/4] i2c: rewrite mvtwsi, support
> orion5x and kirkwood
>
> This rewrite of the mvtwsi driver is 25% smaller and much
> faster and simpler than the previous code.
>
> Signed-off-by: Albert Aribaud <albert.aribaud@free.fr>
> ---
> drivers/i2c/mvtwsi.c | 742
> +++++++++++++++++++++++---------------------------
> 1 files changed, 334 insertions(+), 408 deletions(-)
>
> diff --git a/drivers/i2c/mvtwsi.c b/drivers/i2c/mvtwsi.c
> index a4409be..e7f08ac 100644
> --- a/drivers/i2c/mvtwsi.c
> +++ b/drivers/i2c/mvtwsi.c
> @@ -1,10 +1,7 @@
> /*
> - * Driver for the i2c controller on the Marvell line of host bridges
> - * (e.g, gt642[46]0, mv643[46]0, mv644[46]0, Orion SoC family),
> - * and Kirkwood family.
> + * Driver for the TWSI (i2c) controller on the Marvell orion5x

Don't you think Kirkwood is missing here ?

> *
> - * Based on:
> - * Author: Mark A. Greer <mgreer@mvista.com>
> + * Author: Albert Aribaud <albert.aribaud@free.fr>
> * 2005 (c) MontaVista, Software, Inc.

I hope this line is not there in earlier version, pls confirm..

> *
> * See file CREDITS for list of people who contributed to this
> @@ -24,473 +21,402 @@
> * along with this program; if not, write to the Free Software
> * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
> * MA 02110-1301 USA
> - *
> - * ported from Linux to u-boot
> - * (C) Copyright 2009
> - * Heiko Schocher, DENX Software Engineering, hs at denx.de.
> */
> +
> #include <common.h>
> #include <i2c.h>
> -#include <asm/arch/kirkwood.h>
> #include <asm/errno.h>
> #include <asm/io.h>
>
> -DECLARE_GLOBAL_DATA_PTR;
> +/*
> + * include a file that will provide CONFIG_I2C_MVTWSI_BASE
> + * and possibly other settings
> + */
>
> -static unsigned int i2c_bus_num __attribute__ ((section
> (".data"))) = 0;
> -#if defined(CONFIG_I2C_MUX)
> -static unsigned int i2c_bus_num_mux __attribute__ ((section
> ("data"))) = 0;
> +#if defined(CONFIG_ORION5X)
> +#include <asm/arch/orion5x.h>
> +#else
> +#error Driver mvtwsi not supported by SoC or board
> #endif
>
> -/* Register defines */
> -#define KW_I2C_REG_SLAVE_ADDR 0x00
> -#define KW_I2C_REG_DATA 0x04
> -#define KW_I2C_REG_CONTROL 0x08
> -#define KW_I2C_REG_STATUS 0x0c
> -#define KW_I2C_REG_BAUD 0x0c
> -#define KW_I2C_REG_EXT_SLAVE_ADDR 0x10
> -#define KW_I2C_REG_SOFT_RESET 0x1c
> -
> -#define KW_I2C_REG_CONTROL_ACK 0x00000004
> -#define KW_I2C_REG_CONTROL_IFLG 0x00000008
> -#define KW_I2C_REG_CONTROL_STOP 0x00000010
> -#define KW_I2C_REG_CONTROL_START 0x00000020
> -#define KW_I2C_REG_CONTROL_TWSIEN 0x00000040
> -#define KW_I2C_REG_CONTROL_INTEN 0x00000080
> -
> -/* Ctlr status values */
> -#define KW_I2C_STATUS_BUS_ERR 0x00
> -#define KW_I2C_STATUS_MAST_START 0x08
> -#define KW_I2C_STATUS_MAST_REPEAT_START 0x10
> -#define KW_I2C_STATUS_MAST_WR_ADDR_ACK 0x18
> -#define KW_I2C_STATUS_MAST_WR_ADDR_NO_ACK 0x20
> -#define KW_I2C_STATUS_MAST_WR_ACK 0x28
> -#define KW_I2C_STATUS_MAST_WR_NO_ACK 0x30
> -#define KW_I2C_STATUS_MAST_LOST_ARB 0x38
> -#define KW_I2C_STATUS_MAST_RD_ADDR_ACK 0x40
> -#define KW_I2C_STATUS_MAST_RD_ADDR_NO_ACK 0x48
> -#define KW_I2C_STATUS_MAST_RD_DATA_ACK 0x50
> -#define KW_I2C_STATUS_MAST_RD_DATA_NO_ACK 0x58
> -#define KW_I2C_STATUS_MAST_WR_ADDR_2_ACK 0xd0
> -#define KW_I2C_STATUS_MAST_WR_ADDR_2_NO_ACK 0xd8
> -#define KW_I2C_STATUS_MAST_RD_ADDR_2_ACK 0xe0
> -#define KW_I2C_STATUS_MAST_RD_ADDR_2_NO_ACK 0xe8
> -#define KW_I2C_STATUS_NO_STATUS 0xf8
> -
> -/* Driver states */
> -enum {
> - KW_I2C_STATE_INVALID,
> - KW_I2C_STATE_IDLE,
> - KW_I2C_STATE_WAITING_FOR_START_COND,
> - KW_I2C_STATE_WAITING_FOR_ADDR_1_ACK,
> - KW_I2C_STATE_WAITING_FOR_ADDR_2_ACK,
> - KW_I2C_STATE_WAITING_FOR_SLAVE_ACK,
> - KW_I2C_STATE_WAITING_FOR_SLAVE_DATA,
> -};
> +/*
> + * TWSI register structure
> + */
>
> -/* Driver actions */
> -enum {
> - KW_I2C_ACTION_INVALID,
> - KW_I2C_ACTION_CONTINUE,
> - KW_I2C_ACTION_SEND_START,
> - KW_I2C_ACTION_SEND_ADDR_1,
> - KW_I2C_ACTION_SEND_ADDR_2,
> - KW_I2C_ACTION_SEND_DATA,
> - KW_I2C_ACTION_RCV_DATA,
> - KW_I2C_ACTION_RCV_DATA_STOP,
> - KW_I2C_ACTION_SEND_STOP,
> +struct mvtwsi_registers {
> + u32 slave_address;
> + u32 data;
> + u32 control;
> + union {
> + u32 status; /* when reading */
> + u32 baudrate; /* when writing */
> + };
> + u32 extended_slave_address;

smaller variable names should be preffered

> + u32 reserved[2];
> + u32 soft_reset;
> };
>
> -/* defines to get compatible with Linux driver */
> -#define IRQ_NONE 0x0
> -#define IRQ_HANDLED 0x01
> +/*
> + * Control register fields
> + */
>
> -#define I2C_M_TEN 0x01
> -#define I2C_M_RD 0x02
> -#define I2C_M_REV_DIR_ADDR 0x04;
> +#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
>
> -struct i2c_msg {
> - u32 addr;
> - u32 flags;
> - u8 *buf;
> - u32 len;
> -};
> +/*
> + * 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.
> + */
>
> -struct kirkwood_i2c_data {
> - int irq;
> - u32 state;
> - u32 action;
> - u32 aborting;
> - u32 cntl_bits;
> - void *reg_base;
> - u32 reg_base_p;
> - u32 reg_size;
> - u32 addr1;
> - u32 addr2;
> - u32 bytes_left;
> - u32 byte_posn;
> - u32 block;
> - int rc;
> - u32 freq_m;
> - u32 freq_n;
> - struct i2c_msg *msg;
> -};
> +#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 kirkwood_i2c_data __drv_data __attribute__
> ((section (".data")));
> -static struct kirkwood_i2c_data *drv_data = &__drv_data;
> -static struct i2c_msg __i2c_msg __attribute__ ((section (".data")));
> -static struct i2c_msg *kirkwood_i2c_msg = &__i2c_msg;
> +static struct mvtwsi_registers *twsi =
> + (struct mvtwsi_registers *) CONFIG_I2C_MVTWSI_BASE;
>
> /*
> -
> **************************************************************
> ***************
> - *
> - * Finite State Machine & Interrupt Routines
> - *
> -
> **************************************************************
> ***************
> + * 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.
> */
>
> -static inline int abs(int n)
> -{
> - if(n >= 0)
> - return n;
> - else
> - return n * -1;
> -}
> +#define MVTWSI_ERROR_WRONG_STATUS 0x01
> +#define MVTWSI_ERROR_TIMEOUT 0x02
>
> -static void kirkwood_calculate_speed(int speed)
> -{
> - int calcspeed;
> - int diff;
> - int best_diff = CONFIG_SYS_TCLK;
> - int best_speed = 0;
> - int m, n;
> - int tmp[8] = {2, 4, 8, 16, 32, 64, 128, 256};
> +#define MVTWSI_ERROR(ec, lc, ls, es) (((ec << 24) & 0xFF000000) | \
> + ((lc << 16) & 0x00FF0000) | ((ls<<8) & 0x0000FF00) |
> (es & 0xFF))
>
> - for (n = 0; n < 8; n++) {
> - for (m = 0; m < 16; m++) {
> - calcspeed = CONFIG_SYS_TCLK / (10 * (m
> + 1) * tmp[n]);
> - diff = abs((speed - calcspeed));
> - if ( diff < best_diff) {
> - best_diff = diff;
> - best_speed = calcspeed;
> - drv_data->freq_m = m;
> - drv_data->freq_n = n;
> - }
> +/*
> + * 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);
> }
>
> -/* Reset hardware and initialize FSM */
> -static void
> -kirkwood_i2c_hw_init(int speed, int slaveadd)
> +/*
> + * 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)
> {
> - drv_data->state = KW_I2C_STATE_IDLE;
> -
> - kirkwood_calculate_speed(speed);
> - writel(0, CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_SOFT_RESET);
> - writel((((drv_data->freq_m & 0xf) << 3) |
> (drv_data->freq_n & 0x7)),
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_BAUD);
> - writel(slaveadd, CONFIG_I2C_KW_REG_BASE +
> KW_I2C_REG_SLAVE_ADDR);
> - writel(0, CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_EXT_SLAVE_ADDR);
> - writel(KW_I2C_REG_CONTROL_TWSIEN | KW_I2C_REG_CONTROL_STOP,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> + /* 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);
> }
>
> -static void
> -kirkwood_i2c_fsm(u32 status)
> +/*
> + * Send a byte (i2c address or data).
> + */
> +static int twsi_send(u8 byte, int expected_status)
> {
> - /*
> - * If state is idle, then this is likely the remnants of an old
> - * operation that driver has given up on or the user has killed.
> - * If so, issue the stop condition and go to idle.
> - */
> - if (drv_data->state == KW_I2C_STATE_IDLE) {
> - drv_data->action = KW_I2C_ACTION_SEND_STOP;
> - return;
> - }
> -
> - /* The status from the ctlr [mostly] tells us what to do next */
> - switch (status) {
> - /* Start condition interrupt */
> - case KW_I2C_STATUS_MAST_START: /* 0x08 */
> - case KW_I2C_STATUS_MAST_REPEAT_START: /* 0x10 */
> - drv_data->action = KW_I2C_ACTION_SEND_ADDR_1;
> - drv_data->state = KW_I2C_STATE_WAITING_FOR_ADDR_1_ACK;
> - break;
> -
> - /* Performing a write */
> - case KW_I2C_STATUS_MAST_WR_ADDR_ACK: /* 0x18 */
> - if (drv_data->msg->flags & I2C_M_TEN) {
> - drv_data->action = KW_I2C_ACTION_SEND_ADDR_2;
> - drv_data->state =
> - KW_I2C_STATE_WAITING_FOR_ADDR_2_ACK;
> - break;
> - }
> - /* FALLTHRU */
> - case KW_I2C_STATUS_MAST_WR_ADDR_2_ACK: /* 0xd0 */
> - case KW_I2C_STATUS_MAST_WR_ACK: /* 0x28 */
> - if ((drv_data->bytes_left == 0)
> - || (drv_data->aborting
> - && (drv_data->byte_posn
> != 0))) {
> - drv_data->action = KW_I2C_ACTION_SEND_STOP;
> - drv_data->state = KW_I2C_STATE_IDLE;
> - } else {
> - drv_data->action = KW_I2C_ACTION_SEND_DATA;
> - drv_data->state =
> - KW_I2C_STATE_WAITING_FOR_SLAVE_ACK;
> - drv_data->bytes_left--;
> - }
> - break;
> -
> - /* Performing a read */
> - case KW_I2C_STATUS_MAST_RD_ADDR_ACK: /* 40 */
> - if (drv_data->msg->flags & I2C_M_TEN) {
> - drv_data->action = KW_I2C_ACTION_SEND_ADDR_2;
> - drv_data->state =
> - KW_I2C_STATE_WAITING_FOR_ADDR_2_ACK;
> - break;
> - }
> - /* FALLTHRU */
> - case KW_I2C_STATUS_MAST_RD_ADDR_2_ACK: /* 0xe0 */
> - if (drv_data->bytes_left == 0) {
> - drv_data->action = KW_I2C_ACTION_SEND_STOP;
> - drv_data->state = KW_I2C_STATE_IDLE;
> - break;
> - }
> - /* FALLTHRU */
> - case KW_I2C_STATUS_MAST_RD_DATA_ACK: /* 0x50 */
> - if (status != KW_I2C_STATUS_MAST_RD_DATA_ACK)
> - drv_data->action = KW_I2C_ACTION_CONTINUE;
> - else {
> - drv_data->action = KW_I2C_ACTION_RCV_DATA;
> - drv_data->bytes_left--;
> - }
> - drv_data->state = KW_I2C_STATE_WAITING_FOR_SLAVE_DATA;
> -
> - if ((drv_data->bytes_left == 1) || drv_data->aborting)
> - drv_data->cntl_bits &= ~KW_I2C_REG_CONTROL_ACK;
> - break;
> -
> - case KW_I2C_STATUS_MAST_RD_DATA_NO_ACK: /* 0x58 */
> - drv_data->action = KW_I2C_ACTION_RCV_DATA_STOP;
> - drv_data->state = KW_I2C_STATE_IDLE;
> - break;
> -
> - case KW_I2C_STATUS_MAST_WR_ADDR_NO_ACK: /* 0x20 */
> - case KW_I2C_STATUS_MAST_WR_NO_ACK: /* 30 */
> - case KW_I2C_STATUS_MAST_RD_ADDR_NO_ACK: /* 48 */
> - /* Doesn't seem to be a device at other end */
> - drv_data->action = KW_I2C_ACTION_SEND_STOP;
> - drv_data->state = KW_I2C_STATE_IDLE;
> - drv_data->rc = -ENODEV;
> - break;
> -
> - default:
> - printf("kirkwood_i2c_fsm: Ctlr Error -- state: 0x%x, "
> - "status: 0x%x, addr: 0x%x, flags: 0x%x\n",
> - drv_data->state, status, drv_data->msg->addr,
> - drv_data->msg->flags);
> - drv_data->action = KW_I2C_ACTION_SEND_STOP;
> - kirkwood_i2c_hw_init(CONFIG_SYS_I2C_SPEED,
> CONFIG_SYS_I2C_SLAVE);
> - drv_data->rc = -EIO;
> - }
> + /* 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);
> }
>
> -static void
> -kirkwood_i2c_do_action(void)
> +/*
> + * Receive a byte.
> + * Global mvtwsi_control_flags variable says if we should ack or nak.
> + */
> +static int twsi_recv(u8 *byte)
> {
> - switch(drv_data->action) {
> - case KW_I2C_ACTION_CONTINUE:
> - writel(drv_data->cntl_bits,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_SEND_START:
> - writel(drv_data->cntl_bits | KW_I2C_REG_CONTROL_START,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_SEND_ADDR_1:
> - writel(drv_data->addr1,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_DATA);
> - writel(drv_data->cntl_bits,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_SEND_ADDR_2:
> - writel(drv_data->addr2,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_DATA);
> - writel(drv_data->cntl_bits,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_SEND_DATA:
> - writel(drv_data->msg->buf[drv_data->byte_posn++],
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_DATA);
> - writel(drv_data->cntl_bits,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_RCV_DATA:
> - drv_data->msg->buf[drv_data->byte_posn++] =
> - readl(CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_DATA);
> - writel(drv_data->cntl_bits,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - break;
> -
> - case KW_I2C_ACTION_RCV_DATA_STOP:
> - drv_data->msg->buf[drv_data->byte_posn++] =
> - readl(CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_DATA);
> - drv_data->cntl_bits &= ~KW_I2C_REG_CONTROL_INTEN;
> - writel(drv_data->cntl_bits | KW_I2C_REG_CONTROL_STOP,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - drv_data->block = 0;
> - break;
> -
> - case KW_I2C_ACTION_INVALID:
> - default:
> - printf("kirkwood_i2c_do_action: Invalid action: %d\n",
> - drv_data->action);
> - drv_data->rc = -EIO;
> - /* FALLTHRU */
> - case KW_I2C_ACTION_SEND_STOP:
> - drv_data->cntl_bits &= ~KW_I2C_REG_CONTROL_INTEN;
> - writel(drv_data->cntl_bits | KW_I2C_REG_CONTROL_STOP,
> - CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - drv_data->block = 0;
> - break;
> - }
> + 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;
> }
>
> -static int
> -kirkwood_i2c_intr(void)
> +/*
> + * Assert the STOP condition.
> + * This is also used to force the bus back in idle (SDA=SCL=1).
> + */
> +static int twsi_stop(int status)
> {
> - u32 status;
> - u32 ctrl;
> - int rc = IRQ_NONE;
> -
> - ctrl = readl(CONFIG_I2C_KW_REG_BASE + KW_I2C_REG_CONTROL);
> - while ((ctrl & KW_I2C_REG_CONTROL_IFLG) &&
> - (drv_data->rc == 0)) {
> - status = readl(CONFIG_I2C_KW_REG_BASE +
> KW_I2C_REG_STATUS);
> - kirkwood_i2c_fsm(status);
> - kirkwood_i2c_do_action();
> - rc = IRQ_HANDLED;
> - ctrl = readl(CONFIG_I2C_KW_REG_BASE +
> KW_I2C_REG_CONTROL);
> - udelay(1000);
> - }
> - return rc;
> + 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;
> }
>
> -static void
> -kirkwood_i2c_doio(struct i2c_msg *msg)
> -{
> - int ret;
> +/*
> + * Ugly formula to convert m and n values to a frequency comes from
> + * TWSI specifications
> + */
>
> - while ((drv_data->rc == 0) && (drv_data->state !=
> KW_I2C_STATE_IDLE)) {
> - /* poll Status register */
> - ret = kirkwood_i2c_intr();
> - if (ret == IRQ_NONE)
> - udelay(10);
> - }
> +#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.
> + */
> +
> +static u8 twsi_baud_rate = 0x44;

What does it indicate? pls use figurative constants/macros

> +static u8 twsi_actual_speed = TWSI_FREQUENCY(4, 4);
> +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->extended_slave_address);
> + /* assert STOP but don't care for the result */
> + (void) twsi_stop(0);
> }
>
> -static void
> -kirkwood_i2c_prepare_for_io(struct i2c_msg *msg)
> +/*
> + * 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)
> {
> - u32 dir = 0;
> -
> - drv_data->msg = msg;
> - drv_data->byte_posn = 0;
> - drv_data->bytes_left = msg->len;
> - drv_data->aborting = 0;
> - drv_data->rc = 0;
> - /* in u-boot we use no IRQs */
> - drv_data->cntl_bits = KW_I2C_REG_CONTROL_ACK |
> KW_I2C_REG_CONTROL_TWSIEN;
> -
> - if (msg->flags & I2C_M_RD)
> - dir = 1;
> - if (msg->flags & I2C_M_TEN) {
> - drv_data->addr1 = 0xf0 | (((u32)msg->addr &
> 0x300) >> 7) | dir;
> - drv_data->addr2 = (u32)msg->addr & 0xff;
> - } else {
> - drv_data->addr1 = ((u32)msg->addr & 0x7f) << 1 | dir;
> - drv_data->addr2 = 0;
> + int tmp_speed, highest_speed, n, m;
> + int baud = 0x44; /* value at controller reset */

Same here..

Regards..
Prafulla . .