platform/msm_shared/uart_dm.c

/* Copyright (c) 2010, Code Aurora Forum. All rights reserved.

 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
 *     copyright notice, this list of conditions and the following
 *     disclaimer in the documentation and/or other materials provided
 *     with the distribution.
 *   * Neither the name of Code Aurora Forum, Inc. nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR
 * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
 * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <string.h>
#include <stdlib.h>
#include <debug.h>
#include <reg.h>
#include <sys/types.h>
#include <platform/iomap.h>
#include <platform/irqs.h>
#include <platform/interrupts.h>
#include <platform/clock.h>
#include <platform/gpio.h>
#include <uart_dm.h>
#include <gsbi.h>


#ifndef NULL
#define NULL        0
#endif

/* Note:
 * This is a basic implementation of UART_DM protocol. More focus has been
 * given on simplicity than efficiency. Few of the things to be noted are:
 * - RX path may not be suitable for multi-threaded scenaraio because of the
 *   use of static variables. TX path shouldn't have any problem though. If
 *   multi-threaded support is required, a simple data-structure can
 *   be maintained for each thread.
 * - Right now we are using polling method than interrupt based.
 * - We are using legacy UART protocol without Data Mover.
 * - Not all interrupts and error events are handled.
 * - While waiting Watchdog hasn't been taken into consideration.
 */


#define PACK_CHARS_INTO_WORDS(a, cnt, word)  {                                 \
                                               word = 0;                       \
                                               for(int j=0; j < (int)cnt; j++) \
                                               {                               \
                                                   word |= (a[j] & 0xff)       \
                                                               << (j * 8);     \
                                               }                               \
                                              }


/* Static Function Prototype Declarations */
static unsigned int msm_boot_uart_dm_gsbi_init(uint8_t id);
static unsigned int msm_boot_uart_replace_lr_with_cr(char* data_in,
                                                     int num_of_chars,
                                                     char *data_out,
                                                     int *num_of_chars_out);
static unsigned int msm_boot_uart_dm_init(uint8_t id);
static unsigned int msm_boot_uart_dm_read(uint8_t id, unsigned int* data,
                                          int wait);
static unsigned int msm_boot_uart_dm_write(uint8_t id, char* data,
                                           unsigned int num_of_chars);
static unsigned int msm_boot_uart_dm_init_rx_transfer(uint8_t id);
static unsigned int msm_boot_uart_dm_reset(uint8_t id);

/* Keep track of gsbi vs port mapping.
 */
static uint8_t gsbi_lookup[4];

/* Extern functions */
void udelay(unsigned usecs);


/*
 * Helper function to replace Line Feed char "\n" with
 * Carriage Return "\r\n".
 * Currently keeping it simple than efficient
 */
static unsigned int msm_boot_uart_replace_lr_with_cr(char* data_in,
                                                     int num_of_chars,
                                                     char *data_out,
                                                     int *num_of_chars_out )
{
    int i = 0, j = 0;

    if ((data_in == NULL) || (data_out == NULL) || (num_of_chars < 0))
    {
        return MSM_BOOT_UART_DM_E_INVAL;
    }

    for (i=0, j=0; i < num_of_chars; i++, j++)
    {
        if ( data_in[i] == '\n' )
        {
            data_out[j++] = '\r';
        }

        data_out[j] = data_in[i];
    }

    *num_of_chars_out = j;

    return MSM_BOOT_UART_DM_E_SUCCESS;
}

/*
 * Initialize and configure GSBI for operation
 */
static unsigned int msm_boot_uart_dm_gsbi_init(uint8_t id)
{
    /* Configure the uart clock */
    clock_config_uart_dm(id);

    /* Configure GPIO to provide connectivity between GSBI
       product ports and chip pads */
    gpio_config_uart_dm(id);

    /* Configure Data Mover for GSBI operation.
     * Currently not supported. */

    /* Configure GSBI for UART_DM protocol.
     * I2C on 2 ports, UART (without HS flow control) on the other 2. */
    writel(GSBI_PROTOCOL_CODE_I2C_UART << GSBI_CTRL_REG_PROTOCOL_CODE_S,
           GSBI_CTRL_REG(id));

	/* Configure clock selection register for tx and rx rates.
	 * Selecting 115.2k for both RX and TX.
	 */
	writel(UART_DM_CLK_RX_TX_BIT_RATE, MSM_BOOT_UART_DM_CSR(id));

    return MSM_BOOT_UART_DM_E_SUCCESS;
}

/*
 * Reset the UART
 */
static unsigned int msm_boot_uart_dm_reset(uint8_t id)
{
    writel(MSM_BOOT_UART_DM_CMD_RESET_RX, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CMD_RESET_TX, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CMD_RESET_ERR_STAT, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CMD_RES_TX_ERR, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CMD_RES_STALE_INT, MSM_BOOT_UART_DM_CR(id));

    return MSM_BOOT_UART_DM_E_SUCCESS;
}


/*
 * Initialize UART_DM - configure clock and required registers.
 */
static unsigned int msm_boot_uart_dm_init(uint8_t id)
{
    /* Configure GSBI for uart dm */
    msm_boot_uart_dm_gsbi_init(id);

    /* Configure UART mode registers MR1 and MR2 */
    /* Hardware flow control isn't supported */
    writel(0x0, MSM_BOOT_UART_DM_MR1(id));

    /* 8-N-1 configuration: 8 data bits - No parity - 1 stop bit */
    writel(MSM_BOOT_UART_DM_8_N_1_MODE, MSM_BOOT_UART_DM_MR2(id));

    /* Configure Interrupt Mask register IMR */
    writel(MSM_BOOT_UART_DM_IMR_ENABLED, MSM_BOOT_UART_DM_IMR(id));

    /* Configure Tx and Rx watermarks configuration registers */
    /* TX watermark value is set to 0 - interrupt is generated when
     * FIFO level is less than or equal to 0 */
    writel(MSM_BOOT_UART_DM_TFW_VALUE, MSM_BOOT_UART_DM_TFWR(id));

    /* RX watermark value*/
    writel(MSM_BOOT_UART_DM_RFW_VALUE, MSM_BOOT_UART_DM_RFWR(id));

    /* Configure Interrupt Programming Register*/
    /* Set initial Stale timeout value*/
    writel(MSM_BOOT_UART_DM_STALE_TIMEOUT_LSB, MSM_BOOT_UART_DM_IPR(id));

    /* Configure IRDA if required */
    /* Disabling IRDA mode */
    writel(0x0, MSM_BOOT_UART_DM_IRDA(id));

    /* Configure and enable sim interface if required */

    /* Configure hunt character value in HCR register */
    /* Keep it in reset state */
    writel(0x0, MSM_BOOT_UART_DM_HCR(id));

    /* Configure Rx FIFO base address */
    /* Both TX/RX shares same SRAM and default is half-n-half.
     * Sticking with default value now.
     * As such RAM size is (2^RAM_ADDR_WIDTH, 32-bit entries).
     * We have found RAM_ADDR_WIDTH = 0x7f */

    /* Issue soft reset command */
    msm_boot_uart_dm_reset(id);

    /* Enable/Disable Rx/Tx DM interfaces */
    /* Data Mover not currently utilized. */
    writel(0x0, MSM_BOOT_UART_DM_DMEN(id));


    /* Enable transmitter and receiver */
    writel(MSM_BOOT_UART_DM_CR_RX_ENABLE, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CR_TX_ENABLE, MSM_BOOT_UART_DM_CR(id));

    /* Initialize Receive Path */
    msm_boot_uart_dm_init_rx_transfer(id);

    return MSM_BOOT_UART_DM_E_SUCCESS;
}


/*
 * Initialize Receive Path
 */
static unsigned int msm_boot_uart_dm_init_rx_transfer(uint8_t id)
{
    writel(MSM_BOOT_UART_DM_GCMD_DIS_STALE_EVT, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_CMD_RES_STALE_INT, MSM_BOOT_UART_DM_CR(id));
    writel(MSM_BOOT_UART_DM_DMRX_DEF_VALUE, MSM_BOOT_UART_DM_DMRX(id));
    writel(MSM_BOOT_UART_DM_GCMD_ENA_STALE_EVT, MSM_BOOT_UART_DM_CR(id));

    return MSM_BOOT_UART_DM_E_SUCCESS;
}

/*
 * UART Receive operation
 * Reads a word from the RX FIFO.
 */
static unsigned int msm_boot_uart_dm_read(uint8_t id, unsigned int* data, int wait)
{
    static int rx_last_snap_count = 0;
    static int rx_chars_read_since_last_xfer = 0;

    if (data == NULL)
    {
        return MSM_BOOT_UART_DM_E_INVAL;
    }

    /* We will be polling RXRDY status bit */
    while (!(readl(MSM_BOOT_UART_DM_SR(id)) & MSM_BOOT_UART_DM_SR_RXRDY))
    {
        /* if this is not a blocking call, we'll just return */
        if (!wait)
        {
            return MSM_BOOT_UART_DM_E_RX_NOT_READY;
        }
    }

    /* Check for Overrun error. We'll just reset Error Status */
    if (readl(MSM_BOOT_UART_DM_SR(id)) & MSM_BOOT_UART_DM_SR_UART_OVERRUN)
    {
        writel(MSM_BOOT_UART_DM_CMD_RESET_ERR_STAT, MSM_BOOT_UART_DM_CR(id));
    }

    /* RX FIFO is ready; read a word. */
    *data = readl(MSM_BOOT_UART_DM_RF(id, 0));

    /* increment the total count of chars we've read so far */
    rx_chars_read_since_last_xfer += 4;

     /* Rx transfer ends when one of the conditions is met:
     * - The number of characters received since the end of the previous xfer
     *   equals the value written to DMRX at Transfer Initialization
     * - A stale event occurred
     */

    /* If RX transfer has not ended yet */
    if (rx_last_snap_count == 0)
    {
        /* Check if we've received stale event */
        if (readl(MSM_BOOT_UART_DM_MISR(id)) & MSM_BOOT_UART_DM_RXSTALE)
        {
            /* Send command to reset stale interrupt */
            writel(MSM_BOOT_UART_DM_CMD_RES_STALE_INT, MSM_BOOT_UART_DM_CR(id));
        }

        /* Check if we haven't read more than DMRX value */
        else if ((unsigned int)rx_chars_read_since_last_xfer <
                  readl(MSM_BOOT_UART_DM_DMRX(id)))
        {
            /* We can still continue reading before initializing RX transfer */
            return MSM_BOOT_UART_DM_E_SUCCESS;
        }

        /* If we've reached here it means RX xfer end conditions been met */

        /* Read UART_DM_RX_TOTAL_SNAP register to know how many valid chars
         * we've read so far since last transfer */
        rx_last_snap_count = readl(MSM_BOOT_UART_DM_RX_TOTAL_SNAP(id));

    }

    /* If there are still data left in FIFO we'll read them before
     * initializing RX Transfer again */
    if ((rx_last_snap_count - rx_chars_read_since_last_xfer) >= 0 )
    {
        return MSM_BOOT_UART_DM_E_SUCCESS;
    }

    msm_boot_uart_dm_init_rx_transfer(id);
    rx_last_snap_count = 0;
    rx_chars_read_since_last_xfer = 0;

    return MSM_BOOT_UART_DM_E_SUCCESS;
}

/*
 * UART transmit operation
 */
static unsigned int msm_boot_uart_dm_write(uint8_t id, char* data,
                                           unsigned int num_of_chars)
{
    unsigned int tx_word_count = 0;
    unsigned int tx_char_left = 0, tx_char = 0;
    unsigned int tx_word = 0;
    int i = 0;
    char* tx_data = NULL;
    char new_data[1024];

    if ((data == NULL) || (num_of_chars <= 0))
    {
        return MSM_BOOT_UART_DM_E_INVAL;
    }

    /* Replace line-feed (/n) with carriage-return + line-feed (/r/n) */

    msm_boot_uart_replace_lr_with_cr(data, num_of_chars, new_data, &i);

    tx_data = new_data;
    num_of_chars = i;

    /* Write to NO_CHARS_FOR_TX register number of characters
     * to be transmitted. However, before writing TX_FIFO must
     * be empty as indicated by TX_READY interrupt in IMR register
     */

    /* Check if transmit FIFO is empty.
     * If not we'll wait for TX_READY interrupt. */
    if (!(readl(MSM_BOOT_UART_DM_SR(id)) & MSM_BOOT_UART_DM_SR_TXEMT))
    {
        while (!(readl(MSM_BOOT_UART_DM_ISR(id)) & MSM_BOOT_UART_DM_TX_READY))
        {
            udelay(1);
            /* Kick watchdog? */
        }
    }

    /* We are here. FIFO is ready to be written. */
    /* Write number of characters to be written */
    writel(num_of_chars, MSM_BOOT_UART_DM_NO_CHARS_FOR_TX(id));

    /* Clear TX_READY interrupt */
    writel(MSM_BOOT_UART_DM_GCMD_RES_TX_RDY_INT, MSM_BOOT_UART_DM_CR(id));

    /* We use four-character word FIFO. So we need to divide data into
     * four characters and write in UART_DM_TF register */
    tx_word_count = (num_of_chars % 4)? ((num_of_chars / 4) + 1) :
                                        (num_of_chars / 4);
    tx_char_left = num_of_chars;

    for (i = 0; i < (int)tx_word_count; i++)
    {
        tx_char = (tx_char_left < 4)? tx_char_left : 4;
        PACK_CHARS_INTO_WORDS(tx_data, tx_char, tx_word);

        /* Wait till TX FIFO has space */
        while (!(readl(MSM_BOOT_UART_DM_SR(id)) & MSM_BOOT_UART_DM_SR_TXRDY))
        {
            udelay(1);
        }

        /* TX FIFO has space. Write the chars */
        writel(tx_word, MSM_BOOT_UART_DM_TF(id, 0));
        tx_char_left = num_of_chars - (i+1)*4;
        tx_data = tx_data + 4;
    }

    return MSM_BOOT_UART_DM_E_SUCCESS;
}

/* Defining functions that's exposed to outside world and in coformance to
 * existing uart implemention. These functions are being called to initialize
 * UART and print debug messages in bootloader.
 */
void uart_init(uint8_t gsbi_id)
{
    static uint8_t port = 0;
    char *data = "Android Bootloader - UART_DM Initialized!!!\n";

    msm_boot_uart_dm_init(gsbi_id);
    msm_boot_uart_dm_write(gsbi_id, data, 44);

    ASSERT(port < ARRAY_SIZE(gsbi_lookup));
    gsbi_lookup[port++] = gsbi_id;
}


/* UART_DM uses four character word FIFO where as UART core
 * uses a character FIFO. so it's really inefficient to try
 * to write single character. But that's how dprintf has been
 * implemented.
 */
int uart_putc(int port, char c)
{
    uint8_t gsbi_id = gsbi_lookup[port];

    msm_boot_uart_dm_write(gsbi_id, &c, 1);

    return 0;
}

/* UART_DM uses four character word FIFO whereas uart_getc
 * is supposed to read only one character. So we need to
 * read a word and keep track of each character in the word.
 */
int uart_getc(int port, bool wait)
{
    int byte;
    static unsigned int word = 0;
    uint8_t gsbi_id = gsbi_lookup[port];

    if (!word)
    {
        /* Read from FIFO only if it's a first read or all the four
         * characters out of a word have been read */
        if (msm_boot_uart_dm_read(gsbi_id, &word, wait) !=
            MSM_BOOT_UART_DM_E_SUCCESS)
        {
            return -1;
        }

    }

    byte = (int) word & 0xff;
    word = word >> 8;

    return byte;
}