rockbox/firmware/target/arm/imx233/i2c-imx233.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2011 by Amaury Pouly
 * 
 * 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 software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "config.h"
#include "system.h"
#include "kernel.h"
#include "dma-imx233.h"
#include "i2c-imx233.h"
#include "pinctrl-imx233.h"
#include "string.h"

/**
 * Driver Architecture:
 * The driver has two interfaces: the good'n'old i2c_* api and a more
 * advanced one specific to the imx233 dma architecture. The i2c_* api is
 * implemented with the imx233_i2c_* one.
 * Since each i2c transfer must be split into several dma transfers and we
 * cannot do dynamic allocation, we allow for at most I2C_NR_STAGES stages.
 * A typical read memory transfer will require 3 stages thus 4 is safe:
 * - one with start, device address and memory address
 * - one with repeated start and device address
 * - one with data read and stop
 * To make the interface easier to use and to handle the DMA/cache related
 * issues, all the data transfers are done in a statically allocated buffer
 * which is managed by the driver. The driver will ensure that all transfers
 * are cache aligned and will copy back the data to user buffers at the end.
 * The I2C_BUFFER_SIZE define controls the size of the buffer. All transfers
 * should probably fit within 512 bytes.
 */

/* Used for DMA */
struct i2c_dma_command_t
{
    struct apb_dma_command_t dma;
    /* PIO words */
    uint32_t ctrl0;
    /* copy buffer copy */
    void *src;
    void *dst;
    /* padded to next multiple of cache line size (32 bytes) */
    uint32_t pad[2];
} __attribute__((packed)) CACHEALIGN_ATTR;

__ENSURE_STRUCT_CACHE_FRIENDLY(struct i2c_dma_command_t)

#define I2C_NR_STAGES   4
#define I2C_BUFFER_SIZE 512
/* Current transfer */
static int i2c_nr_stages;
static struct i2c_dma_command_t i2c_stage[I2C_NR_STAGES];
static struct mutex i2c_mutex;
static struct semaphore i2c_sema;
static uint8_t i2c_buffer[I2C_BUFFER_SIZE] CACHEALIGN_ATTR;
static uint32_t i2c_buffer_end; /* current end */

void INT_I2C_DMA(void)
{
    /* reset dma channel on error */
    if(imx233_dma_is_channel_error_irq(APB_I2C))
        imx233_dma_reset_channel(APB_I2C);
    /* clear irq flags */
    imx233_dma_clear_channel_interrupt(APB_I2C);
    semaphore_release(&i2c_sema);
}

void INT_I2C_ERROR(void)
{
    /* reset dma channel on error */
    if(imx233_dma_is_channel_error_irq(APB_I2C))
        imx233_dma_reset_channel(APB_I2C);
    /* clear irq flags */
    imx233_dma_clear_channel_interrupt(APB_I2C);
    semaphore_release(&i2c_sema);
}

static void imx233_i2c_reset(void)
{
    /* clear softreset */
    imx233_reset_block(&HW_I2C_CTRL0);
    /* Errata (imx233):
     * When RETAIN_CLOCK is set, the ninth clock pulse (ACK) is not generated. However, the SDA
     * line is read at the proper timing interval. If RETAIN_CLOCK is cleared, the ninth clock pulse is
     * generated.
     * HW_I2C_CTRL1[ACK_MODE] has default value of 0. It should be set to 1 to enable the fix for
     * this issue.
     */
#if IMX233_SUBTARGET >= 3780
    BF_SET(I2C_CTRL1, ACK_MODE);
#endif
    BF_SET(I2C_CTRL0, CLKGATE);
    /* Fast-mode @ 400K */
    HW_I2C_TIMING0 = 0x000F0007; /* tHIGH=0.6us, read at 0.3us */
    HW_I2C_TIMING1 = 0x001F000F; /* tLOW=1.3us, write at 0.6us */
    HW_I2C_TIMING2 = 0x0015000D;
}

void imx233_i2c_init(void)
{
    BF_SET(I2C_CTRL0, SFTRST);
    /* setup pins (must be done when shutdown) */
    imx233_pinctrl_setup_vpin(VPIN_I2C_SCL, "i2c scl", PINCTRL_DRIVE_4mA, true);
    imx233_pinctrl_setup_vpin(VPIN_I2C_SDA, "i2c sda", PINCTRL_DRIVE_4mA, true);
    imx233_i2c_reset();
    mutex_init(&i2c_mutex);
    semaphore_init(&i2c_sema, 1, 0);
}

void imx233_i2c_begin(void)
{
    mutex_lock(&i2c_mutex);
    /* wakeup */
    BF_CLR(I2C_CTRL0, CLKGATE);
    i2c_nr_stages = 0;
    i2c_buffer_end = 0;
}

enum imx233_i2c_error_t imx233_i2c_add(bool start, bool transmit, void *buffer, unsigned size, bool stop)
{
    if(i2c_nr_stages == I2C_NR_STAGES)
        return I2C_ERROR;
    /* align buffer end on cache boundary */
    uint32_t start_off = CACHEALIGN_UP(i2c_buffer_end);
    uint32_t end_off = start_off + size;
    if(end_off > I2C_BUFFER_SIZE)
    {
        panicf("die");
        return I2C_BUFFER_FULL;
    }
    i2c_buffer_end = end_off;
    if(transmit)
    {
        /* copy data to buffer */
        memcpy(i2c_buffer + start_off, buffer, size);
    }
    else
    {
        /* record pointers for finalization */
        i2c_stage[i2c_nr_stages].src = i2c_buffer + start_off;
        i2c_stage[i2c_nr_stages].dst = buffer;
    }
    
    if(i2c_nr_stages > 0)
    {
        i2c_stage[i2c_nr_stages - 1].dma.next = &i2c_stage[i2c_nr_stages].dma;
        i2c_stage[i2c_nr_stages - 1].dma.cmd |= BM_APB_CHx_CMD_CHAIN;
        if(!start)
            i2c_stage[i2c_nr_stages - 1].ctrl0 |= BM_I2C_CTRL0_RETAIN_CLOCK;
    }
    i2c_stage[i2c_nr_stages].dma.buffer = i2c_buffer + start_off;
    i2c_stage[i2c_nr_stages].dma.next = NULL;
    i2c_stage[i2c_nr_stages].dma.cmd = BF_OR4(APB_CHx_CMD,
        COMMAND(transmit ? BV_APB_CHx_CMD_COMMAND__READ : BV_APB_CHx_CMD_COMMAND__WRITE),
        WAIT4ENDCMD(1), CMDWORDS(1), XFER_COUNT(size));
    /* assume that any read is final (send nak on last) */
    i2c_stage[i2c_nr_stages].ctrl0 = BF_OR6(I2C_CTRL0,
        XFER_COUNT(size), DIRECTION(transmit), SEND_NAK_ON_LAST(!transmit),
        PRE_SEND_START(start), POST_SEND_STOP(stop), MASTER_MODE(1));
    i2c_nr_stages++;
    return I2C_SUCCESS;
}

static enum imx233_i2c_error_t imx233_i2c_finalize(void)
{
    discard_dcache_range(i2c_buffer, I2C_BUFFER_SIZE);
    for(int i = 0; i < i2c_nr_stages; i++)
    {
        struct i2c_dma_command_t *c = &i2c_stage[i];
        if(BF_RDX(c->dma.cmd, APB_CHx_CMD, COMMAND) == BV_APB_CHx_CMD_COMMAND__WRITE)
            memcpy(c->dst, c->src, BF_RDX(c->dma.cmd, APB_CHx_CMD, XFER_COUNT));
    }
    return I2C_SUCCESS;
}

enum imx233_i2c_error_t imx233_i2c_end(unsigned timeout)
{
    if(i2c_nr_stages == 0)
        return I2C_ERROR;
    i2c_stage[i2c_nr_stages - 1].dma.cmd |= BM_APB_CHx_CMD_SEMAPHORE | BM_APB_CHx_CMD_IRQONCMPLT;

    BF_CLR(I2C_CTRL1, ALL_IRQ);
    imx233_dma_reset_channel(APB_I2C);
    imx233_icoll_enable_interrupt(INT_SRC_I2C_DMA, true);
    imx233_icoll_enable_interrupt(INT_SRC_I2C_ERROR, true);
    imx233_dma_enable_channel_interrupt(APB_I2C, true);
    imx233_dma_start_command(APB_I2C, &i2c_stage[0].dma);

    enum imx233_i2c_error_t ret;
    if(semaphore_wait(&i2c_sema, timeout) == OBJ_WAIT_TIMEDOUT)
    {
        imx233_dma_reset_channel(APB_I2C);
        imx233_i2c_reset();
        ret = I2C_TIMEOUT;
    }
    else if(BF_RD(I2C_CTRL1, MASTER_LOSS_IRQ))
        ret = I2C_MASTER_LOSS;
    else if(BF_RD(I2C_CTRL1, NO_SLAVE_ACK_IRQ))
    {
        /* the core doesn't like this error, this is a workaround to prevent lock up */
#if IMX233_SUBTARGET >= 3780
        BF_SET(I2C_CTRL1, CLR_GOT_A_NAK);
#endif
        imx233_dma_reset_channel(APB_I2C);
        imx233_i2c_reset();
        ret = I2C_NO_SLAVE_ACK;
    }
    else if(BF_RD(I2C_CTRL1, EARLY_TERM_IRQ))
        ret = I2C_SLAVE_NAK;
    else
        ret = imx233_i2c_finalize();
    /* sleep */
    BF_SET(I2C_CTRL0, CLKGATE);
    mutex_unlock(&i2c_mutex);
    return ret;
}

void i2c_init(void)
{
}

int i2c_write(int device, const unsigned char* buf, int count)
{
    uint8_t addr = device;
    imx233_i2c_begin();
    imx233_i2c_add(true, true, &addr, 1, false); /* start + dev addr */
    imx233_i2c_add(false, true, (void *)buf, count, true); /* data + stop */
    return imx233_i2c_end(10);
}

int i2c_read(int device, unsigned char* buf, int count)
{
    uint8_t addr = device | 1;
    imx233_i2c_begin();
    imx233_i2c_add(true, true, &addr, 1, false); /* start + dev addr */
    imx233_i2c_add(false, false, buf, count, true); /* data + stop */
    return imx233_i2c_end(10);
}

int i2c_readmem(int device, int address, unsigned char* buf, int count)
{
    uint8_t start[2] = {device, address};
    uint8_t addr_rd = device | 1;
    imx233_i2c_begin();
    imx233_i2c_add(true, true, start, 2, false); /* start + dev addr + addr */
    imx233_i2c_add(true, true, &addr_rd, 1, false); /* start + dev addr */
    imx233_i2c_add(false, false, buf, count, true); /* data + stop */
    return imx233_i2c_end(10);
}

int i2c_writemem(int device, int address, const unsigned char* buf, int count)
{
    uint8_t start[2] = {device, address};
    imx233_i2c_begin();
    imx233_i2c_add(true, true, start, 2, false); /* start + dev addr + addr */
    imx233_i2c_add(false, true, (void *)buf, count, true); /* data + stop */
    return imx233_i2c_end(10);
}