am335xgpio.c

Go to the documentation of this file.

// SPDX-License-Identifier: GPL-2.0-or-later
 
/***************************************************************************
 *   Copyright (C) 2022 by Steve Marple, stevemarple@googlemail.com        *
 *                                                                         *
 *   Based on bcm2835gpio.c and linuxgpiod.c                               *
 ***************************************************************************/
 
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
 
#include <jtag/adapter.h>
#include <jtag/interface.h>
#include <transport/transport.h>
#include "bitbang.h"
 
#include <sys/mman.h>
 
/* GPIO register base addresses. Values taken from "AM335x and AMIC110 Sitara
 * Processors Technical Reference Manual", Chapter 2 Memory Map.
 */
#define AM335XGPIO_NUM_GPIO_PER_CHIP 32
#define AM335XGPIO_NUM_GPIO_CHIPS 4
#define AM335XGPIO_GPIO0_HW_ADDR 0x44E07000
#define AM335XGPIO_GPIO1_HW_ADDR 0x4804C000
#define AM335XGPIO_GPIO2_HW_ADDR 0x481AC000
#define AM335XGPIO_GPIO3_HW_ADDR 0x481AE000
 
/* 32-bit offsets from GPIO chip base address. Values taken from "AM335x and
 * AMIC110 Sitara Processors Technical Reference Manual", Chapter 25
 * General-Purpose Input/Output.
 */
#define AM335XGPIO_GPIO_OE_OFFSET (0x134 / 4)
#define AM335XGPIO_GPIO_DATAIN_OFFSET (0x138 / 4)
#define AM335XGPIO_GPIO_DATAOUT_OFFSET (0x13C / 4)  /* DATAOUT register uses 0 for output, 1 for input */
#define AM335XGPIO_GPIO_CLEARDATAOUT_OFFSET (0x190 / 4)
#define AM335XGPIO_GPIO_SETDATAOUT_OFFSET (0x194 / 4)
 
#define AM335XGPIO_READ_REG(chip_num, offset) \
    (*(am335xgpio_gpio_chip_mmap_addr[(chip_num)] + (offset)))
 
#define AM335XGPIO_WRITE_REG(chip_num, offset, value) \
    (*(am335xgpio_gpio_chip_mmap_addr[(chip_num)] + (offset)) = (value))
 
#define AM335XGPIO_SET_REG_BITS(chip_num, offset, bit_mask) \
    (*(am335xgpio_gpio_chip_mmap_addr[(chip_num)] + (offset)) |= (bit_mask))
 
#define AM335XGPIO_CLEAR_REG_BITS(chip_num, offset, bit_mask) \
    (*(am335xgpio_gpio_chip_mmap_addr[(chip_num)] + (offset)) &= ~(bit_mask))
 
#define AM335XGPIO_SET_INPUT(gpio_config) \
    AM335XGPIO_SET_REG_BITS((gpio_config)->chip_num, AM335XGPIO_GPIO_OE_OFFSET, BIT((gpio_config)->gpio_num))
#define AM335XGPIO_SET_OUTPUT(gpio_config) \
    AM335XGPIO_CLEAR_REG_BITS((gpio_config)->chip_num, AM335XGPIO_GPIO_OE_OFFSET, BIT((gpio_config)->gpio_num))
#define AM335XGPIO_SET_HIGH(gpio_config) \
    AM335XGPIO_WRITE_REG((gpio_config)->chip_num, AM335XGPIO_GPIO_SETDATAOUT_OFFSET, BIT((gpio_config)->gpio_num))
#define AM335XGPIO_SET_LOW(gpio_config) \
    AM335XGPIO_WRITE_REG((gpio_config)->chip_num, AM335XGPIO_GPIO_CLEARDATAOUT_OFFSET, BIT((gpio_config)->gpio_num))
 
enum amx335gpio_initial_gpio_mode {
    AM335XGPIO_GPIO_MODE_INPUT,
    AM335XGPIO_GPIO_MODE_OUTPUT_LOW,
    AM335XGPIO_GPIO_MODE_OUTPUT_HIGH,
};
 
static const uint32_t am335xgpio_gpio_chip_hw_addr[AM335XGPIO_NUM_GPIO_CHIPS] = {
    AM335XGPIO_GPIO0_HW_ADDR,
    AM335XGPIO_GPIO1_HW_ADDR,
    AM335XGPIO_GPIO2_HW_ADDR,
    AM335XGPIO_GPIO3_HW_ADDR,
};
 
/* Memory-mapped address pointers */
static volatile uint32_t *am335xgpio_gpio_chip_mmap_addr[AM335XGPIO_NUM_GPIO_CHIPS];
 
static int dev_mem_fd;
static enum amx335gpio_initial_gpio_mode initial_gpio_mode[ADAPTER_GPIO_IDX_NUM];
 
/* Transition delay coefficients */
static int speed_coeff = 600000;
static int speed_offset = 575;
static unsigned int jtag_delay;
 
static const struct adapter_gpio_config *adapter_gpio_config;
 
static bool is_gpio_config_valid(const struct adapter_gpio_config *gpio_config)
{
    return gpio_config->chip_num >= 0
        && gpio_config->chip_num < AM335XGPIO_NUM_GPIO_CHIPS
        && gpio_config->gpio_num >= 0
        && gpio_config->gpio_num < AM335XGPIO_NUM_GPIO_PER_CHIP;
}
 
static int get_gpio_value(const struct adapter_gpio_config *gpio_config)
{
    unsigned int shift = gpio_config->gpio_num;
    uint32_t value = AM335XGPIO_READ_REG(gpio_config->chip_num, AM335XGPIO_GPIO_DATAIN_OFFSET);
    value = (value >> shift) & 1;
    return value ^ (gpio_config->active_low ? 1 : 0);
}
 
static void set_gpio_value(const struct adapter_gpio_config *gpio_config, int value)
{
    value = value ^ (gpio_config->active_low ? 1 : 0);
    switch (gpio_config->drive) {
    case ADAPTER_GPIO_DRIVE_MODE_PUSH_PULL:
        if (value)
            AM335XGPIO_SET_HIGH(gpio_config);
        else
            AM335XGPIO_SET_LOW(gpio_config);
        /* For performance reasons assume the GPIO is already set as an output
         * and therefore the call can be omitted here.
         */
        break;
    case ADAPTER_GPIO_DRIVE_MODE_OPEN_DRAIN:
        if (value) {
            AM335XGPIO_SET_INPUT(gpio_config);
        } else {
            AM335XGPIO_SET_LOW(gpio_config);
            AM335XGPIO_SET_OUTPUT(gpio_config);
        }
        break;
    case ADAPTER_GPIO_DRIVE_MODE_OPEN_SOURCE:
        if (value) {
            AM335XGPIO_SET_HIGH(gpio_config);
            AM335XGPIO_SET_OUTPUT(gpio_config);
        } else {
            AM335XGPIO_SET_INPUT(gpio_config);
        }
        break;
    }
}
 
static enum amx335gpio_initial_gpio_mode get_gpio_mode(const struct adapter_gpio_config *gpio_config)
{
    if (AM335XGPIO_READ_REG(gpio_config->chip_num, AM335XGPIO_GPIO_OE_OFFSET) & BIT(gpio_config->gpio_num))
        return AM335XGPIO_GPIO_MODE_INPUT;
 
    /* Return output level too so that pin mode can be fully restored */
    if (AM335XGPIO_READ_REG(gpio_config->chip_num, AM335XGPIO_GPIO_DATAOUT_OFFSET) & BIT(gpio_config->gpio_num))
        return AM335XGPIO_GPIO_MODE_OUTPUT_HIGH;
    return AM335XGPIO_GPIO_MODE_OUTPUT_LOW;
}
 
static const char *get_gpio_mode_name(enum amx335gpio_initial_gpio_mode gpio_mode)
{
    switch (gpio_mode) {
    case AM335XGPIO_GPIO_MODE_INPUT:
        return "input";
    case AM335XGPIO_GPIO_MODE_OUTPUT_LOW:
        return "output (low)";
    case AM335XGPIO_GPIO_MODE_OUTPUT_HIGH:
        return "output (high)";
    }
    return "unknown";
}
 
static void initialize_gpio(enum adapter_gpio_config_index idx)
{
    if (!is_gpio_config_valid(&adapter_gpio_config[idx]))
        return;
 
    initial_gpio_mode[idx] = get_gpio_mode(&adapter_gpio_config[idx]);
    LOG_DEBUG("saved GPIO mode for %s (GPIO %d %d): %s",
            adapter_gpio_get_name(idx), adapter_gpio_config[idx].chip_num, adapter_gpio_config[idx].gpio_num,
            get_gpio_mode_name(initial_gpio_mode[idx]));
 
    if (adapter_gpio_config[idx].pull != ADAPTER_GPIO_PULL_NONE) {
        LOG_WARNING("am335xgpio does not support pull-up or pull-down settings (signal %s)",
            adapter_gpio_get_name(idx));
    }
 
    switch (adapter_gpio_config[idx].init_state) {
    case ADAPTER_GPIO_INIT_STATE_INACTIVE:
        set_gpio_value(&adapter_gpio_config[idx], 0);
        break;
    case ADAPTER_GPIO_INIT_STATE_ACTIVE:
        set_gpio_value(&adapter_gpio_config[idx], 1);
        break;
    case ADAPTER_GPIO_INIT_STATE_INPUT:
        AM335XGPIO_SET_INPUT(&adapter_gpio_config[idx]);
        break;
    }
 
    /* Direction for non push-pull is already set by set_gpio_value() */
    if (adapter_gpio_config[idx].drive == ADAPTER_GPIO_DRIVE_MODE_PUSH_PULL)
        AM335XGPIO_SET_OUTPUT(&adapter_gpio_config[idx]);
}
 
static void restore_gpio(enum adapter_gpio_config_index idx)
{
    if (is_gpio_config_valid(&adapter_gpio_config[idx])) {
        switch (initial_gpio_mode[idx]) {
        case AM335XGPIO_GPIO_MODE_INPUT:
            AM335XGPIO_SET_INPUT(&adapter_gpio_config[idx]);
            break;
        case AM335XGPIO_GPIO_MODE_OUTPUT_LOW:
            AM335XGPIO_SET_LOW(&adapter_gpio_config[idx]);
            AM335XGPIO_SET_OUTPUT(&adapter_gpio_config[idx]);
            break;
        case AM335XGPIO_GPIO_MODE_OUTPUT_HIGH:
            AM335XGPIO_SET_HIGH(&adapter_gpio_config[idx]);
            AM335XGPIO_SET_OUTPUT(&adapter_gpio_config[idx]);
            break;
        }
    }
}
 
static bb_value_t am335xgpio_read(void)
{
    return get_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_TDO]) ? BB_HIGH : BB_LOW;
}
 
static int am335xgpio_write(int tck, int tms, int tdi)
{
    set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_TDI], tdi);
    set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_TMS], tms);
    set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_TCK], tck); /* Write clock last */
 
    for (unsigned int i = 0; i < jtag_delay; ++i)
        asm volatile ("");
 
    return ERROR_OK;
}
 
static int am335xgpio_swd_write(int swclk, int swdio)
{
    set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO], swdio);
    set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWCLK], swclk); /* Write clock last */
 
    for (unsigned int i = 0; i < jtag_delay; ++i)
        asm volatile ("");
 
    return ERROR_OK;
}
 
/* (1) assert or (0) deassert reset lines */
static int am335xgpio_reset(int trst, int srst)
{
    /* As the "adapter reset_config" command keeps the srst and trst gpio drive
     * mode settings in sync we can use our standard set_gpio_value() function
     * that honours drive mode and active low.
     */
    if (is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_SRST]))
        set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SRST], srst);
 
    if (is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_TRST]))
        set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_TRST], trst);
 
    LOG_DEBUG("am335xgpio_reset(%d, %d), trst_gpio: %d %d, srst_gpio: %d %d",
        trst, srst,
        adapter_gpio_config[ADAPTER_GPIO_IDX_TRST].chip_num, adapter_gpio_config[ADAPTER_GPIO_IDX_TRST].gpio_num,
        adapter_gpio_config[ADAPTER_GPIO_IDX_SRST].chip_num, adapter_gpio_config[ADAPTER_GPIO_IDX_SRST].gpio_num);
    return ERROR_OK;
}
 
static void am335xgpio_swdio_drive(bool is_output)
{
    if (is_output) {
        if (is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO_DIR]))
            set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO_DIR], 1);
        AM335XGPIO_SET_OUTPUT(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO]);
    } else {
        AM335XGPIO_SET_INPUT(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO]);
        if (is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO_DIR]))
            set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO_DIR], 0);
    }
}
 
static int am335xgpio_swdio_read(void)
{
    return get_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO]);
}
 
static int am335xgpio_blink(int on)
{
    if (is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_LED]))
        set_gpio_value(&adapter_gpio_config[ADAPTER_GPIO_IDX_LED], on);
 
    return ERROR_OK;
}
 
static struct bitbang_interface am335xgpio_bitbang = {
    .read = am335xgpio_read,
    .write = am335xgpio_write,
    .swdio_read = am335xgpio_swdio_read,
    .swdio_drive = am335xgpio_swdio_drive,
    .swd_write = am335xgpio_swd_write,
    .blink = am335xgpio_blink
};
 
static int am335xgpio_khz(int khz, int *jtag_speed)
{
    if (!khz) {
        LOG_DEBUG("RCLK not supported");
        return ERROR_FAIL;
    }
    *jtag_speed = speed_coeff / khz - speed_offset;
    if (*jtag_speed < 0)
        *jtag_speed = 0;
    return ERROR_OK;
}
 
static int am335xgpio_speed_div(int speed, int *khz)
{
    *khz = speed_coeff / (speed + speed_offset);
    return ERROR_OK;
}
 
static int am335xgpio_speed(int speed)
{
    jtag_delay = speed;
    return ERROR_OK;
}
 
COMMAND_HANDLER(am335xgpio_handle_speed_coeffs)
{
    if (CMD_ARGC == 2) {
        COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], speed_coeff);
        COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], speed_offset);
    }
 
    command_print(CMD, "AM335x GPIO config: speed_coeffs = %d, speed_offset = %d",
                  speed_coeff, speed_offset);
    return ERROR_OK;
}
 
static const struct command_registration am335xgpio_subcommand_handlers[] = {
    {
        .name = "speed_coeffs",
        .handler = am335xgpio_handle_speed_coeffs,
        .mode = COMMAND_CONFIG,
        .help = "SPEED_COEFF and SPEED_OFFSET for delay calculations.",
        .usage = "[SPEED_COEFF SPEED_OFFSET]",
    },
    COMMAND_REGISTRATION_DONE
};
 
static const struct command_registration am335xgpio_command_handlers[] = {
    {
        .name = "am335xgpio",
        .mode = COMMAND_ANY,
        .help = "perform am335xgpio management",
        .chain = am335xgpio_subcommand_handlers,
        .usage = "",
    },
    COMMAND_REGISTRATION_DONE
};
 
static const char * const am335xgpio_transports[] = { "jtag", "swd", NULL };
 
static struct jtag_interface am335xgpio_interface = {
    .supported = DEBUG_CAP_TMS_SEQ,
    .execute_queue = bitbang_execute_queue,
};
 
static bool am335xgpio_jtag_mode_possible(void)
{
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_TCK]))
        return false;
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_TMS]))
        return false;
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_TDI]))
        return false;
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_TDO]))
        return false;
    return true;
}
 
static bool am335xgpio_swd_mode_possible(void)
{
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWCLK]))
        return false;
    if (!is_gpio_config_valid(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO]))
        return false;
    return true;
}
 
static void am335xgpio_munmap(void)
{
    for (unsigned int i = 0; i < AM335XGPIO_NUM_GPIO_CHIPS && am335xgpio_gpio_chip_mmap_addr[i] != MAP_FAILED; ++i)
        if (munmap((void *)am335xgpio_gpio_chip_mmap_addr[i], sysconf(_SC_PAGE_SIZE)) < 0)
            LOG_ERROR("Cannot unmap GPIO memory for chip %d: %s", i, strerror(errno));
}
 
static int am335xgpio_init(void)
{
    LOG_INFO("AM335x GPIO JTAG/SWD bitbang driver");
 
    bitbang_interface = &am335xgpio_bitbang;
    adapter_gpio_config = adapter_gpio_get_config();
 
    if (transport_is_jtag() && !am335xgpio_jtag_mode_possible()) {
        LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode");
        return ERROR_JTAG_INIT_FAILED;
    }
 
    if (transport_is_swd() && !am335xgpio_swd_mode_possible()) {
        LOG_ERROR("Require swclk and swdio gpio for SWD mode");
        return ERROR_JTAG_INIT_FAILED;
    }
 
    dev_mem_fd = open("/dev/gpiomem", O_RDWR | O_SYNC);
    if (dev_mem_fd < 0) {
        LOG_DEBUG("Cannot open /dev/gpiomem, fallback to /dev/mem");
        dev_mem_fd = open("/dev/mem", O_RDWR | O_SYNC);
    }
    if (dev_mem_fd < 0) {
        LOG_ERROR("open: %s", strerror(errno));
        return ERROR_JTAG_INIT_FAILED;
    }
 
    for (unsigned int i = 0; i < AM335XGPIO_NUM_GPIO_CHIPS; ++i) {
        am335xgpio_gpio_chip_mmap_addr[i] = mmap(NULL, sysconf(_SC_PAGE_SIZE), PROT_READ | PROT_WRITE,
                MAP_SHARED, dev_mem_fd, am335xgpio_gpio_chip_hw_addr[i]);
 
        if (am335xgpio_gpio_chip_mmap_addr[i] == MAP_FAILED) {
            LOG_ERROR("mmap: %s", strerror(errno));
            am335xgpio_munmap();
            close(dev_mem_fd);
            return ERROR_JTAG_INIT_FAILED;
        }
    }
    close(dev_mem_fd);
 
    /* Configure JTAG/SWD signals. Default directions and initial states are handled
     * by adapter.c and "adapter gpio" command.
     */
    if (transport_is_jtag()) {
        initialize_gpio(ADAPTER_GPIO_IDX_TDO);
        initialize_gpio(ADAPTER_GPIO_IDX_TDI);
        initialize_gpio(ADAPTER_GPIO_IDX_TMS);
        initialize_gpio(ADAPTER_GPIO_IDX_TCK);
        initialize_gpio(ADAPTER_GPIO_IDX_TRST);
    }
 
    if (transport_is_swd()) {
        /* swdio and its buffer should be initialized in the order that prevents
         * two outputs from being connected together. This will occur if the
         * swdio GPIO of the AM335x is configured as an output while its
         * external buffer is configured to send the swdio signal from the
         * target to the AM335x.
         */
        if (adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO].init_state == ADAPTER_GPIO_INIT_STATE_INPUT) {
            initialize_gpio(ADAPTER_GPIO_IDX_SWDIO);
            initialize_gpio(ADAPTER_GPIO_IDX_SWDIO_DIR);
        } else {
            initialize_gpio(ADAPTER_GPIO_IDX_SWDIO_DIR);
            initialize_gpio(ADAPTER_GPIO_IDX_SWDIO);
        }
 
        initialize_gpio(ADAPTER_GPIO_IDX_SWCLK);
    }
 
    initialize_gpio(ADAPTER_GPIO_IDX_SRST);
    initialize_gpio(ADAPTER_GPIO_IDX_LED);
 
    return ERROR_OK;
}
 
static int am335xgpio_quit(void)
{
    if (transport_is_jtag()) {
        restore_gpio(ADAPTER_GPIO_IDX_TDO);
        restore_gpio(ADAPTER_GPIO_IDX_TDI);
        restore_gpio(ADAPTER_GPIO_IDX_TMS);
        restore_gpio(ADAPTER_GPIO_IDX_TCK);
        restore_gpio(ADAPTER_GPIO_IDX_TRST);
    }
 
    if (transport_is_swd()) {
        /* Restore swdio/swdio_dir to their initial modes, even if that means
         * connecting two outputs. Begin by making swdio an input so that the
         * current and final states of swdio and swdio_dir do not have to be
         * considered to calculate the safe restoration order.
         */
        AM335XGPIO_SET_INPUT(&adapter_gpio_config[ADAPTER_GPIO_IDX_SWDIO]);
        restore_gpio(ADAPTER_GPIO_IDX_SWDIO_DIR);
        restore_gpio(ADAPTER_GPIO_IDX_SWDIO);
 
        restore_gpio(ADAPTER_GPIO_IDX_SWCLK);
    }
 
    restore_gpio(ADAPTER_GPIO_IDX_SRST);
    restore_gpio(ADAPTER_GPIO_IDX_LED);
 
    am335xgpio_munmap();
 
    return ERROR_OK;
}
 
struct adapter_driver am335xgpio_adapter_driver = {
    .name = "am335xgpio",
    .transports = am335xgpio_transports,
    .commands = am335xgpio_command_handlers,
 
    .init = am335xgpio_init,
    .quit = am335xgpio_quit,
    .reset = am335xgpio_reset,
    .speed = am335xgpio_speed,
    .khz = am335xgpio_khz,
    .speed_div = am335xgpio_speed_div,
 
    .jtag_ops = &am335xgpio_interface,
    .swd_ops = &bitbang_swd,
};