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zephyr/drivers/fpga/fpga_ice40.c

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/*
* Copyright (c) 2022 Meta
*
* SPDX-License-Identifier: Apache-2.0
*/
#define DT_DRV_COMPAT lattice_ice40_fpga
#include <stdbool.h>
#include <stdio.h>
#include <zephyr/device.h>
#include <zephyr/drivers/fpga.h>
#include <zephyr/drivers/gpio.h>
#ifdef CONFIG_PINCTRL
#include <zephyr/drivers/pinctrl.h>
#endif
#include <zephyr/drivers/spi.h>
#include <zephyr/kernel.h>
#include <zephyr/logging/log.h>
#include <zephyr/sys/crc.h>
/*
* Note: When loading a bitstream, the iCE40 has a 'quirk' in that the CS
* polarity must be inverted during the 'leading clocks' phase and
* 'trailing clocks' phase. While the bitstream is being transmitted, the
* CS polarity is normal (active low). Zephyr's SPI driver model currently
* does not handle these types of quirks (in contrast to e.g. Linux).
*
* The logical alternative would be to put the CS into GPIO mode, perform 3
* separate SPI transfers (inverting CS polarity as necessary) and then
* restore the default pinctrl settings. On some higher-end microcontrollers
* and microprocessors, it's possible to do that without breaking the iCE40
* timing requirements.
*
* However, on lower-end microcontrollers, the amount of time that elapses
* between SPI transfers does break the iCE40 timing requirements. That
* leaves us with the bitbanging option. Of course, on lower-end
* microcontrollers, the amount of time required to execute something
* like gpio_pin_configure_dt() dwarfs the 2*500 nanoseconds needed to
* achieve the minimum 1 MHz clock rate for loading the iCE40 bistream. So
* in order to bitbang on lower-end microcontrollers, we actually require
* direct register access to the set and clear registers.
*
* With that, this driver is left with 2 possible modes of operation which
* are:
* - FPGA_ICE40_LOAD_MODE_SPI (for higher-end microcontrollers)
* - FPGA_ICE40_LOAD_MODE_GPIO (for lower-end microcontrollers)
*/
#define FPGA_ICE40_LOAD_MODE_SPI 0
#define FPGA_ICE40_LOAD_MODE_GPIO 1
#ifndef BITS_PER_NIBBLE
#define BITS_PER_NIBBLE 4
#endif
#ifndef BITS_PER_BYTE
#define BITS_PER_BYTE 8
#endif
#ifndef NIBBLES_PER_BYTE
#define NIBBLES_PER_BYTE (BITS_PER_BYTE / BITS_PER_NIBBLE)
#endif
/*
* Values in Hz, intentionally to be comparable with the spi-max-frequency
* property from DT bindings in spi-device.yaml.
*/
#define FPGA_ICE40_SPI_HZ_MIN 1000000
#define FPGA_ICE40_SPI_HZ_MAX 25000000
#define FPGA_ICE40_CRESET_DELAY_US_MIN 1 /* 200ns absolute minimum */
#define FPGA_ICE40_CONFIG_DELAY_US_MIN 1200
#define FPGA_ICE40_LEADING_CLOCKS_MIN 8
#define FPGA_ICE40_TRAILING_CLOCKS_MIN 49
LOG_MODULE_REGISTER(fpga_ice40);
struct fpga_ice40_data {
uint32_t crc;
/* simply use crc32 as info */
char info[2 * sizeof(uint32_t) + 1];
bool on;
bool loaded;
struct k_spinlock lock;
};
struct fpga_ice40_config {
struct spi_dt_spec bus;
struct gpio_dt_spec cdone;
struct gpio_dt_spec creset;
struct gpio_dt_spec clk;
struct gpio_dt_spec pico;
volatile gpio_port_pins_t *set;
volatile gpio_port_pins_t *clear;
uint16_t mhz_delay_count;
uint16_t creset_delay_us;
uint16_t config_delay_us;
uint8_t leading_clocks;
uint8_t trailing_clocks;
fpga_api_load load;
#ifdef CONFIG_PINCTRL
const struct pinctrl_dev_config *pincfg;
#endif
};
static void fpga_ice40_crc_to_str(uint32_t crc, char *s)
{
char ch;
uint8_t i;
uint8_t nibble;
const char *table = "0123456789abcdef";
for (i = 0; i < sizeof(crc) * NIBBLES_PER_BYTE; ++i, crc >>= BITS_PER_NIBBLE) {
nibble = crc & GENMASK(BITS_PER_NIBBLE, 0);
ch = table[nibble];
s[sizeof(crc) * NIBBLES_PER_BYTE - i - 1] = ch;
}
s[sizeof(crc) * NIBBLES_PER_BYTE] = '\0';
}
/*
* This is a calibrated delay loop used to achieve a 1 MHz SPI_CLK frequency
* with FPGA_ICE40_LOAD_MODE_GPIO. It is used both in fpga_ice40_send_clocks()
* and fpga_ice40_spi_send_data().
*
* Calibration is achieved via the mhz_delay_count device tree parameter. See
* lattice,ice40-fpga.yaml for details.
*/
static inline void fpga_ice40_delay(size_t n)
{
for (; n > 0; --n) {
__asm__ __volatile__("");
}
}
static void fpga_ice40_send_clocks(size_t delay, volatile gpio_port_pins_t *set,
volatile gpio_port_pins_t *clear, gpio_port_pins_t clk, size_t n)
{
for (; n > 0; --n) {
*clear |= clk;
fpga_ice40_delay(delay);
*set |= clk;
fpga_ice40_delay(delay);
}
}
static void fpga_ice40_spi_send_data(size_t delay, volatile gpio_port_pins_t *set,
volatile gpio_port_pins_t *clear, gpio_port_pins_t cs,
gpio_port_pins_t clk, gpio_port_pins_t pico, uint8_t *z,
size_t n)
{
bool hi;
/* assert chip-select (active low) */
*clear |= cs;
for (; n > 0; --n, ++z) {
/* msb down to lsb */
for (int b = 7; b >= 0; --b) {
/* Data is shifted out on the falling edge (CPOL=0) */
*clear |= clk;
fpga_ice40_delay(delay);
hi = !!(BIT(b) & *z);
if (hi) {
*set |= pico;
} else {
*clear |= pico;
}
/* Data is sampled on the rising edge (CPHA=0) */
*set |= clk;
fpga_ice40_delay(delay);
}
}
/* de-assert chip-select (active low) */
*set |= cs;
}
static enum FPGA_status fpga_ice40_get_status(const struct device *dev)
{
enum FPGA_status st;
k_spinlock_key_t key;
struct fpga_ice40_data *data = dev->data;
key = k_spin_lock(&data->lock);
if (data->loaded && data->on) {
st = FPGA_STATUS_ACTIVE;
} else {
st = FPGA_STATUS_INACTIVE;
}
k_spin_unlock(&data->lock, key);
return st;
}
/*
* See iCE40 Family Handbook, Appendix A. SPI Slave Configuration Procedure,
* pp 15-21.
*
* https://www.latticesemi.com/~/media/LatticeSemi/Documents/Handbooks/iCE40FamilyHandbook.pdf
*/
static int fpga_ice40_load_gpio(const struct device *dev, uint32_t *image_ptr, uint32_t img_size)
{
int ret;
uint32_t crc;
gpio_port_pins_t cs;
gpio_port_pins_t clk;
k_spinlock_key_t key;
gpio_port_pins_t pico;
gpio_port_pins_t creset;
struct fpga_ice40_data *data = dev->data;
const struct fpga_ice40_config *config = dev->config;
/* prepare masks */
cs = BIT(config->bus.config.cs.gpio.pin);
clk = BIT(config->clk.pin);
pico = BIT(config->pico.pin);
creset = BIT(config->creset.pin);
/* crc check */
crc = crc32_ieee((uint8_t *)image_ptr, img_size);
if (data->loaded && crc == data->crc) {
LOG_WRN("already loaded with image CRC32c: 0x%08x", data->crc);
}
key = k_spin_lock(&data->lock);
/* clear crc */
data->crc = 0;
data->loaded = false;
fpga_ice40_crc_to_str(0, data->info);
LOG_DBG("Initializing GPIO");
ret = gpio_pin_configure_dt(&config->cdone, GPIO_INPUT) ||
gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH) ||
gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH) ||
gpio_pin_configure_dt(&config->clk, GPIO_OUTPUT_HIGH) ||
gpio_pin_configure_dt(&config->pico, GPIO_OUTPUT_HIGH);
__ASSERT(ret == 0, "Failed to initialize GPIO: %d", ret);
LOG_DBG("Set CRESET low");
LOG_DBG("Set SPI_CS low");
*config->clear |= (creset | cs);
/* Wait a minimum of 200ns */
LOG_DBG("Delay %u us", config->creset_delay_us);
fpga_ice40_delay(2 * config->mhz_delay_count * config->creset_delay_us);
__ASSERT(gpio_pin_get_dt(&config->cdone) == 0, "CDONE was not high");
LOG_DBG("Set CRESET high");
*config->set |= creset;
LOG_DBG("Delay %u us", config->config_delay_us);
k_busy_wait(config->config_delay_us);
LOG_DBG("Set SPI_CS high");
*config->set |= cs;
LOG_DBG("Send %u clocks", config->leading_clocks);
fpga_ice40_send_clocks(config->mhz_delay_count, config->set, config->clear, clk,
config->leading_clocks);
LOG_DBG("Set SPI_CS low");
LOG_DBG("Send bin file");
LOG_DBG("Set SPI_CS high");
fpga_ice40_spi_send_data(config->mhz_delay_count, config->set, config->clear, cs, clk, pico,
(uint8_t *)image_ptr, img_size);
LOG_DBG("Send %u clocks", config->trailing_clocks);
fpga_ice40_send_clocks(config->mhz_delay_count, config->set, config->clear, clk,
config->trailing_clocks);
LOG_DBG("checking CDONE");
ret = gpio_pin_get_dt(&config->cdone);
if (ret < 0) {
LOG_ERR("failed to read CDONE: %d", ret);
goto unlock;
} else if (ret != 1) {
ret = -EIO;
LOG_ERR("CDONE did not go high");
goto unlock;
}
ret = 0;
data->loaded = true;
fpga_ice40_crc_to_str(crc, data->info);
LOG_INF("Loaded image with CRC32 0x%08x", crc);
unlock:
(void)gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH);
(void)gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH);
(void)gpio_pin_configure_dt(&config->clk, GPIO_DISCONNECTED);
(void)gpio_pin_configure_dt(&config->pico, GPIO_DISCONNECTED);
#ifdef CONFIG_PINCTRL
(void)pinctrl_apply_state(config->pincfg, PINCTRL_STATE_DEFAULT);
#endif
k_spin_unlock(&data->lock, key);
return ret;
}
static int fpga_ice40_load_spi(const struct device *dev, uint32_t *image_ptr, uint32_t img_size)
{
int ret;
uint32_t crc;
k_spinlock_key_t key;
struct spi_buf tx_buf;
const struct spi_buf_set tx_bufs = {
.buffers = &tx_buf,
.count = 1,
};
struct fpga_ice40_data *data = dev->data;
uint8_t clock_buf[(UINT8_MAX + 1) / BITS_PER_BYTE];
const struct fpga_ice40_config *config = dev->config;
/* crc check */
crc = crc32_ieee((uint8_t *)image_ptr, img_size);
if (data->loaded && crc == data->crc) {
LOG_WRN("already loaded with image CRC32c: 0x%08x", data->crc);
}
key = k_spin_lock(&data->lock);
/* clear crc */
data->crc = 0;
data->loaded = false;
fpga_ice40_crc_to_str(0, data->info);
LOG_DBG("Initializing GPIO");
ret = gpio_pin_configure_dt(&config->cdone, GPIO_INPUT) ||
gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH) ||
gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH);
__ASSERT(ret == 0, "Failed to initialize GPIO: %d", ret);
LOG_DBG("Set CRESET low");
ret = gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_LOW);
if (ret < 0) {
LOG_ERR("failed to set CRESET low: %d", ret);
goto unlock;
}
LOG_DBG("Set SPI_CS low");
ret = gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_LOW);
if (ret < 0) {
LOG_ERR("failed to set SPI_CS low: %d", ret);
goto unlock;
}
/* Wait a minimum of 200ns */
LOG_DBG("Delay %u us", config->creset_delay_us);
k_usleep(config->creset_delay_us);
__ASSERT(gpio_pin_get_dt(&config->cdone) == 0, "CDONE was not high");
LOG_DBG("Set CRESET high");
ret = gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH);
if (ret < 0) {
LOG_ERR("failed to set CRESET high: %d", ret);
goto unlock;
}
LOG_DBG("Delay %u us", config->config_delay_us);
k_busy_wait(config->config_delay_us);
LOG_DBG("Set SPI_CS high");
ret = gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH);
if (ret < 0) {
LOG_ERR("failed to set SPI_CS high: %d", ret);
goto unlock;
}
LOG_DBG("Send %u clocks", config->leading_clocks);
tx_buf.buf = clock_buf;
tx_buf.len = DIV_ROUND_UP(config->leading_clocks, BITS_PER_BYTE);
ret = spi_write_dt(&config->bus, &tx_bufs);
if (ret < 0) {
LOG_ERR("Failed to send leading %u clocks: %d", config->leading_clocks, ret);
goto unlock;
}
LOG_DBG("Set SPI_CS low");
ret = gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_LOW);
if (ret < 0) {
LOG_ERR("failed to set SPI_CS low: %d", ret);
goto unlock;
}
LOG_DBG("Send bin file");
tx_buf.buf = image_ptr;
tx_buf.len = img_size;
ret = spi_write_dt(&config->bus, &tx_bufs);
if (ret < 0) {
LOG_ERR("Failed to send bin file: %d", ret);
goto unlock;
}
LOG_DBG("Set SPI_CS high");
ret = gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH);
if (ret < 0) {
LOG_ERR("failed to set SPI_CS high: %d", ret);
goto unlock;
}
LOG_DBG("Send %u clocks", config->trailing_clocks);
tx_buf.buf = clock_buf;
tx_buf.len = DIV_ROUND_UP(config->trailing_clocks, BITS_PER_BYTE);
ret = spi_write_dt(&config->bus, &tx_bufs);
if (ret < 0) {
LOG_ERR("Failed to send trailing %u clocks: %d", config->trailing_clocks, ret);
goto unlock;
}
LOG_DBG("checking CDONE");
ret = gpio_pin_get_dt(&config->cdone);
if (ret < 0) {
LOG_ERR("failed to read CDONE: %d", ret);
goto unlock;
} else if (ret != 1) {
ret = -EIO;
LOG_ERR("CDONE did not go high");
goto unlock;
}
ret = 0;
data->loaded = true;
fpga_ice40_crc_to_str(crc, data->info);
LOG_INF("Loaded image with CRC32 0x%08x", crc);
unlock:
(void)gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH);
(void)gpio_pin_configure_dt(&config->bus.config.cs.gpio, GPIO_OUTPUT_HIGH);
#ifdef CONFIG_PINCTRL
(void)pinctrl_apply_state(config->pincfg, PINCTRL_STATE_DEFAULT);
#endif
k_spin_unlock(&data->lock, key);
return ret;
}
static int fpga_ice40_load(const struct device *dev, uint32_t *image_ptr, uint32_t img_size)
{
const struct fpga_ice40_config *config = dev->config;
return config->load(dev, image_ptr, img_size);
}
static int fpga_ice40_on_off(const struct device *dev, bool on)
{
int ret;
k_spinlock_key_t key;
struct fpga_ice40_data *data = dev->data;
const struct fpga_ice40_config *config = dev->config;
key = k_spin_lock(&data->lock);
ret = gpio_pin_configure_dt(&config->creset, on ? GPIO_OUTPUT_HIGH : GPIO_OUTPUT_LOW);
if (ret < 0) {
goto unlock;
}
data->on = on;
ret = 0;
unlock:
k_spin_unlock(&data->lock, key);
return ret;
}
static int fpga_ice40_on(const struct device *dev)
{
return fpga_ice40_on_off(dev, true);
}
static int fpga_ice40_off(const struct device *dev)
{
return fpga_ice40_on_off(dev, false);
}
static int fpga_ice40_reset(const struct device *dev)
{
return fpga_ice40_off(dev) || fpga_ice40_on(dev);
}
static const char *fpga_ice40_get_info(const struct device *dev)
{
struct fpga_ice40_data *data = dev->data;
return data->info;
}
static const struct fpga_driver_api fpga_ice40_api = {
.get_status = fpga_ice40_get_status,
.reset = fpga_ice40_reset,
.load = fpga_ice40_load,
.on = fpga_ice40_on,
.off = fpga_ice40_off,
.get_info = fpga_ice40_get_info,
};
static int fpga_ice40_init(const struct device *dev)
{
int ret;
const struct fpga_ice40_config *config = dev->config;
ret = gpio_pin_configure_dt(&config->creset, GPIO_OUTPUT_HIGH);
if (ret < 0) {
LOG_ERR("failed to configure CRESET: %d", ret);
return ret;
}
ret = gpio_pin_configure_dt(&config->cdone, 0);
if (ret < 0) {
LOG_ERR("Failed to initialize CDONE: %d", ret);
return ret;
}
return 0;
}
#define FPGA_ICE40_BUS_FREQ(inst) DT_INST_PROP(inst, spi_max_frequency)
#define FPGA_ICE40_CONFIG_DELAY_US(inst) \
DT_INST_PROP_OR(inst, config_delay_us, FPGA_ICE40_CONFIG_DELAY_US_MIN)
#define FPGA_ICE40_CRESET_DELAY_US(inst) \
DT_INST_PROP_OR(inst, creset_delay_us, FPGA_ICE40_CRESET_DELAY_US_MIN)
#define FPGA_ICE40_LEADING_CLOCKS(inst) \
DT_INST_PROP_OR(inst, leading_clocks, FPGA_ICE40_LEADING_CLOCKS_MIN)
#define FPGA_ICE40_TRAILING_CLOCKS(inst) \
DT_INST_PROP_OR(inst, trailing_clocks, FPGA_ICE40_TRAILING_CLOCKS_MIN)
#define FPGA_ICE40_MHZ_DELAY_COUNT(inst) DT_INST_PROP_OR(inst, mhz_delay_count, 0)
#define FPGA_ICE40_GPIO_PINS(inst, name) (volatile gpio_port_pins_t *)DT_INST_PROP_OR(inst, name, 0)
#define FPGA_ICE40_LOAD_MODE(inst) DT_INST_PROP(inst, load_mode)
#define FPGA_ICE40_LOAD_FUNC(inst) \
(FPGA_ICE40_LOAD_MODE(inst) == FPGA_ICE40_LOAD_MODE_SPI \
? fpga_ice40_load_spi \
: (FPGA_ICE40_LOAD_MODE(inst) == FPGA_ICE40_LOAD_MODE_GPIO ? fpga_ice40_load_gpio \
: NULL))
#ifdef CONFIG_PINCTRL
#define FPGA_ICE40_PINCTRL_CONFIG(inst) .pincfg = PINCTRL_DT_DEV_CONFIG_GET(DT_INST_PARENT(inst)),
#define FPGA_ICE40_PINCTRL_DEFINE(inst) PINCTRL_DT_DEFINE(DT_INST_PARENT(inst))
#else
#define FPGA_ICE40_PINCTRL_CONFIG(inst)
#define FPGA_ICE40_PINCTRL_DEFINE(inst)
#endif
#define FPGA_ICE40_DEFINE(inst) \
BUILD_ASSERT(FPGA_ICE40_LOAD_MODE(inst) == FPGA_ICE40_LOAD_MODE_SPI || \
FPGA_ICE40_LOAD_MODE(inst) == FPGA_ICE40_LOAD_MODE_GPIO); \
BUILD_ASSERT(FPGA_ICE40_BUS_FREQ(inst) >= FPGA_ICE40_SPI_HZ_MIN); \
BUILD_ASSERT(FPGA_ICE40_BUS_FREQ(inst) <= FPGA_ICE40_SPI_HZ_MAX); \
BUILD_ASSERT(FPGA_ICE40_CONFIG_DELAY_US(inst) >= FPGA_ICE40_CONFIG_DELAY_US_MIN); \
BUILD_ASSERT(FPGA_ICE40_CONFIG_DELAY_US(inst) <= UINT16_MAX); \
BUILD_ASSERT(FPGA_ICE40_CRESET_DELAY_US(inst) >= FPGA_ICE40_CRESET_DELAY_US_MIN); \
BUILD_ASSERT(FPGA_ICE40_CRESET_DELAY_US(inst) <= UINT16_MAX); \
BUILD_ASSERT(FPGA_ICE40_LEADING_CLOCKS(inst) >= FPGA_ICE40_LEADING_CLOCKS_MIN); \
BUILD_ASSERT(FPGA_ICE40_LEADING_CLOCKS(inst) <= UINT8_MAX); \
BUILD_ASSERT(FPGA_ICE40_TRAILING_CLOCKS(inst) >= FPGA_ICE40_TRAILING_CLOCKS_MIN); \
BUILD_ASSERT(FPGA_ICE40_TRAILING_CLOCKS(inst) <= UINT8_MAX); \
BUILD_ASSERT(FPGA_ICE40_MHZ_DELAY_COUNT(inst) >= 0); \
\
FPGA_ICE40_PINCTRL_DEFINE(inst); \
static struct fpga_ice40_data fpga_ice40_data_##inst; \
\
static const struct fpga_ice40_config fpga_ice40_config_##inst = { \
.bus = SPI_DT_SPEC_INST_GET(inst, SPI_WORD_SET(8) | SPI_TRANSFER_MSB, 0), \
.creset = GPIO_DT_SPEC_INST_GET(inst, creset_gpios), \
.cdone = GPIO_DT_SPEC_INST_GET(inst, cdone_gpios), \
.clk = GPIO_DT_SPEC_INST_GET_OR(inst, clk_gpios, {0}), \
.pico = GPIO_DT_SPEC_INST_GET_OR(inst, pico_gpios, {0}), \
.set = FPGA_ICE40_GPIO_PINS(inst, gpios_set_reg), \
.clear = FPGA_ICE40_GPIO_PINS(inst, gpios_clear_reg), \
.mhz_delay_count = FPGA_ICE40_MHZ_DELAY_COUNT(inst), \
.config_delay_us = FPGA_ICE40_CONFIG_DELAY_US(inst), \
.creset_delay_us = FPGA_ICE40_CRESET_DELAY_US(inst), \
.leading_clocks = FPGA_ICE40_LEADING_CLOCKS(inst), \
.trailing_clocks = FPGA_ICE40_TRAILING_CLOCKS(inst), \
.load = FPGA_ICE40_LOAD_FUNC(inst), \
FPGA_ICE40_PINCTRL_CONFIG(inst)}; \
\
DEVICE_DT_INST_DEFINE(inst, fpga_ice40_init, NULL, &fpga_ice40_data_##inst, \
&fpga_ice40_config_##inst, POST_KERNEL, CONFIG_FPGA_INIT_PRIORITY, \
&fpga_ice40_api);
DT_INST_FOREACH_STATUS_OKAY(FPGA_ICE40_DEFINE)
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