xref: /optee_os/core/drivers/stm32_iwdg.c (revision 077bbb8ad801af6e5ff0808194513ab1d996d77e)

// SPDX-License-Identifier: BSD-3-Clause
/*
 * Copyright (c) 2017-2022, STMicroelectronics - All Rights Reserved
 */

#include <assert.h>
#include <drivers/clk.h>
#include <drivers/clk_dt.h>
#include <drivers/stm32_iwdg.h>
#include <drivers/wdt.h>
#include <io.h>
#include <keep.h>
#include <kernel/boot.h>
#include <kernel/delay.h>
#include <kernel/dt.h>
#include <kernel/dt_driver.h>
#include <kernel/interrupt.h>
#include <kernel/misc.h>
#include <kernel/panic.h>
#include <kernel/pm.h>
#include <kernel/spinlock.h>
#include <libfdt.h>
#include <mm/core_memprot.h>
#include <sm/sm.h>
#include <stm32_util.h>
#include <string.h>
#include <trace.h>

/* IWDG Compatibility */
#define IWDG_TIMEOUT_US		U(1000)
#define IWDG_CNT_MASK		GENMASK_32(11, 0)

/* IWDG registers offsets */
#define IWDG_KR_OFFSET		U(0x00)
#define IWDG_PR_OFFSET		U(0x04)
#define IWDG_RLR_OFFSET		U(0x08)
#define IWDG_SR_OFFSET		U(0x0C)
#define IWDG_EWCR_OFFSET	U(0x14)

#define IWDG_KR_ACCESS_KEY	U(0x5555)
#define IWDG_KR_RELOAD_KEY	U(0xAAAA)
#define IWDG_KR_START_KEY	U(0xCCCC)

/* Use a fixed prescaler divider of 256 */
#define IWDG_PRESCALER_256	U(256)
#define IWDG_PR_DIV_256		U(0x06)
#define IWDG_PR_DIV_MASK	GENMASK_32(3, 0)

#define IWDG_SR_PVU		BIT(0)
#define IWDG_SR_RVU		BIT(1)
#define IWDG_SR_WVU		BIT(2)
#define IWDG_SR_EWU		BIT(3)
#define IWDG_SR_UPDATE_MASK	(IWDG_SR_PVU | IWDG_SR_RVU | IWDG_SR_WVU | \
				 IWDG_SR_EWU)

#define IWDG_EWCR_EWIE		BIT(15)
#define IWDG_EWCR_EWIC		BIT(14)

/*
 * Values for struct stm32_iwdg_device::flags
 * IWDG_FLAGS_HW_ENABLED                Watchdog is enabled by BootROM
 * IWDG_FLAGS_DISABLE_ON_STOP           Watchdog is freezed in SoC STOP mode
 * IWDG_FLAGS_DISABLE_ON_STANDBY        Watchdog is freezed in SoC STANDBY mode
 * IWDG_FLAGS_NON_SECURE                Instance is assigned to non-secure world
 * IWDG_FLAGS_ENABLED			Watchdog has been enabled
 */
#define IWDG_FLAGS_HW_ENABLED			BIT(0)
#define IWDG_FLAGS_DISABLE_ON_STOP		BIT(1)
#define IWDG_FLAGS_DISABLE_ON_STANDBY		BIT(2)
#define IWDG_FLAGS_NON_SECURE			BIT(3)
#define IWDG_FLAGS_ENABLED			BIT(4)

/*
 * IWDG watch instance data
 * @base - IWDG interface IOMEM base address
 * @clock - Bus clock
 * @clk_lsi - IWDG source clock
 * @flags - Property flags for the IWDG instance
 * @timeout - Watchdog elaspure timeout
 * @wdt_chip - Wathcdog chip instance
 * @link - Link in registered watchdog instance list
 */
struct stm32_iwdg_device {
	struct io_pa_va base;
	struct clk *clock;
	struct clk *clk_lsi;
	uint32_t flags;
	unsigned long timeout;
	struct wdt_chip wdt_chip;
	SLIST_ENTRY(stm32_iwdg_device) link;
};

static unsigned int iwdg_lock = SPINLOCK_UNLOCK;

static SLIST_HEAD(iwdg_dev_list_head, stm32_iwdg_device) iwdg_dev_list =
	SLIST_HEAD_INITIALIZER(iwdg_dev_list_head);

static vaddr_t get_base(struct stm32_iwdg_device *iwdg)
{
	return io_pa_or_va(&iwdg->base, 1);
}

static bool is_assigned_to_nsec(struct stm32_iwdg_device *iwdg)
{
	return iwdg->flags & IWDG_FLAGS_NON_SECURE;
}

static bool is_enable(struct stm32_iwdg_device *iwdg)
{
	return iwdg->flags & IWDG_FLAGS_ENABLED;
}

/* Return counter value to related to input timeout in seconds, or 0 on error */
static uint32_t iwdg_timeout_cnt(struct stm32_iwdg_device *iwdg,
				 unsigned long to_sec)
{
	uint64_t reload = (uint64_t)to_sec * clk_get_rate(iwdg->clk_lsi);
	uint64_t cnt = (reload / IWDG_PRESCALER_256) - 1;

	/* Be safe and expect any counter to be above 2 */
	if (cnt > IWDG_CNT_MASK || cnt < 3)
		return 0;

	return cnt;
}

/* Wait IWDG programming completes */
static TEE_Result iwdg_wait_sync(struct stm32_iwdg_device *iwdg)
{
	uint64_t timeout_ref = timeout_init_us(IWDG_TIMEOUT_US);
	vaddr_t iwdg_base = get_base(iwdg);

	while (io_read32(iwdg_base + IWDG_SR_OFFSET) & IWDG_SR_UPDATE_MASK)
		if (timeout_elapsed(timeout_ref))
			break;

	if (io_read32(iwdg_base + IWDG_SR_OFFSET) & IWDG_SR_UPDATE_MASK)
		return TEE_ERROR_GENERIC;

	return TEE_SUCCESS;
}

static TEE_Result configure_timeout(struct stm32_iwdg_device *iwdg)
{
	TEE_Result res = TEE_ERROR_GENERIC;
	vaddr_t iwdg_base = get_base(iwdg);
	uint32_t rlr_value = 0;

	assert(is_enable(iwdg));

	rlr_value = iwdg_timeout_cnt(iwdg, iwdg->timeout);
	if (!rlr_value)
		return TEE_ERROR_GENERIC;

	clk_enable(iwdg->clock);

	io_write32(iwdg_base + IWDG_KR_OFFSET, IWDG_KR_ACCESS_KEY);
	io_write32(iwdg_base + IWDG_PR_OFFSET, IWDG_PR_DIV_256);
	io_write32(iwdg_base + IWDG_RLR_OFFSET, rlr_value);
	io_write32(iwdg_base + IWDG_KR_OFFSET, IWDG_KR_RELOAD_KEY);

	res = iwdg_wait_sync(iwdg);

	clk_disable(iwdg->clock);

	return res;
}

static void iwdg_start(struct stm32_iwdg_device *iwdg)
{
	clk_enable(iwdg->clock);
	io_write32(get_base(iwdg) + IWDG_KR_OFFSET, IWDG_KR_START_KEY);
	clk_disable(iwdg->clock);

	iwdg->flags |= IWDG_FLAGS_ENABLED;
}

static void iwdg_refresh(struct stm32_iwdg_device *iwdg)
{
	clk_enable(iwdg->clock);
	io_write32(get_base(iwdg) + IWDG_KR_OFFSET, IWDG_KR_RELOAD_KEY);
	clk_disable(iwdg->clock);
}

/* Operators for watchdog OP-TEE interface */
static struct stm32_iwdg_device *wdt_chip_to_iwdg(struct wdt_chip *chip)
{
	return container_of(chip, struct stm32_iwdg_device, wdt_chip);
}

static void iwdg_wdt_start(struct wdt_chip *chip)
{
	struct stm32_iwdg_device *iwdg = wdt_chip_to_iwdg(chip);

	iwdg_start(iwdg);

	if (configure_timeout(iwdg))
		panic();
}

static void iwdg_wdt_refresh(struct wdt_chip *chip)
{
	struct stm32_iwdg_device *iwdg = wdt_chip_to_iwdg(chip);

	iwdg_refresh(iwdg);
}

static TEE_Result iwdg_wdt_set_timeout(struct wdt_chip *chip,
				       unsigned long timeout)
{
	struct stm32_iwdg_device *iwdg = wdt_chip_to_iwdg(chip);

	if (!iwdg_timeout_cnt(iwdg, timeout))
		return TEE_ERROR_BAD_PARAMETERS;

	iwdg->timeout = timeout;

	if (is_enable(iwdg)) {
		TEE_Result res = TEE_ERROR_GENERIC;

		res = configure_timeout(iwdg);
		if (res)
			return res;
	}

	return TEE_SUCCESS;
}

static const struct wdt_ops stm32_iwdg_ops = {
	.start = iwdg_wdt_start,
	.ping = iwdg_wdt_refresh,
	.set_timeout = iwdg_wdt_set_timeout,
};
DECLARE_KEEP_PAGER(stm32_iwdg_ops);

/* Refresh all registered watchdogs */
void stm32_iwdg_refresh(void)
{
	struct stm32_iwdg_device *iwdg = NULL;
	uint32_t exceptions = cpu_spin_lock_xsave(&iwdg_lock);

	SLIST_FOREACH(iwdg, &iwdg_dev_list, link)
		iwdg_refresh(iwdg);

	cpu_spin_unlock_xrestore(&iwdg_lock, exceptions);
}

/* Driver initialization */
static TEE_Result stm32_iwdg_parse_fdt(struct stm32_iwdg_device *iwdg,
				       const void *fdt, int node)
{
	TEE_Result res = TEE_ERROR_GENERIC;
	struct dt_node_info dt_info = { };
	const fdt32_t *cuint = NULL;

	fdt_fill_device_info(fdt, &dt_info, node);

	if (dt_info.reg == DT_INFO_INVALID_REG ||
	    dt_info.reg_size == DT_INFO_INVALID_REG_SIZE)
		panic();

	res = clk_dt_get_by_name(fdt, node, "pclk", &iwdg->clock);
	if (res)
		return res;

	res = clk_dt_get_by_name(fdt, node, "lsi", &iwdg->clk_lsi);
	if (res)
		return res;

	if (dt_info.status == DT_STATUS_OK_NSEC)
		iwdg->flags |= IWDG_FLAGS_NON_SECURE;

	/* Get IOMEM address */
	iwdg->base.pa = dt_info.reg;

	if (iwdg->flags & IWDG_FLAGS_NON_SECURE)
		io_pa_or_va_nsec(&iwdg->base, dt_info.reg_size);
	else
		io_pa_or_va_secure(&iwdg->base, dt_info.reg_size);

	assert(iwdg->base.va);

	/* Get and check timeout value */
	cuint = fdt_getprop(fdt, node, "timeout-sec", NULL);
	if (!cuint)
		return TEE_ERROR_BAD_PARAMETERS;

	iwdg->timeout = (int)fdt32_to_cpu(*cuint);
	if (!iwdg->timeout)
		return TEE_ERROR_BAD_PARAMETERS;

	if (!iwdg_timeout_cnt(iwdg, iwdg->timeout)) {
		EMSG("Timeout %lu not applicable", iwdg->timeout);
		return TEE_ERROR_BAD_PARAMETERS;
	}

	/* DT can specify low power cases */
	if (!fdt_getprop(fdt, node, "stm32,enable-on-stop", NULL))
		iwdg->flags |= IWDG_FLAGS_DISABLE_ON_STOP;

	if (!fdt_getprop(fdt, node, "stm32,enable-on-standby", NULL))
		iwdg->flags |= IWDG_FLAGS_DISABLE_ON_STANDBY;

	return TEE_SUCCESS;
}

/* Platform should override this function to provide IWDG fuses configuration */
TEE_Result __weak stm32_get_iwdg_otp_config(paddr_t pbase __unused,
					    struct stm32_iwdg_otp_data *otp_d)
{
	otp_d->hw_enabled = false;
	otp_d->disable_on_stop = false;
	otp_d->disable_on_standby = false;

	return TEE_SUCCESS;
}

static TEE_Result stm32_iwdg_setup(struct stm32_iwdg_device *iwdg,
				   const void *fdt, int node)
{
	struct stm32_iwdg_otp_data otp_data = { };
	TEE_Result res = TEE_SUCCESS;

	res = stm32_iwdg_parse_fdt(iwdg, fdt, node);
	if (res)
		return res;

	res = stm32_get_iwdg_otp_config(iwdg->base.pa, &otp_data);
	if (res)
		return res;

	if (otp_data.hw_enabled)
		iwdg->flags |= IWDG_FLAGS_HW_ENABLED;
	if (otp_data.disable_on_stop)
		iwdg->flags |= IWDG_FLAGS_DISABLE_ON_STOP;
	if (otp_data.disable_on_standby)
		iwdg->flags |= IWDG_FLAGS_DISABLE_ON_STANDBY;

	/* Enable watchdog source clock once for all */
	clk_enable(iwdg->clk_lsi);

	if (otp_data.hw_enabled) {
		iwdg->flags |= IWDG_FLAGS_ENABLED;

		/* Configure timeout if watchdog is already enabled */
		res = configure_timeout(iwdg);
		if (res)
			return res;

		iwdg_refresh(iwdg);
	}

	return TEE_SUCCESS;
}

static TEE_Result stm32_iwdg_register(struct stm32_iwdg_device *iwdg)
{
	TEE_Result res = TEE_ERROR_GENERIC;

	if (is_assigned_to_nsec(iwdg)) {
		stm32mp_register_non_secure_periph_iomem(iwdg->base.pa);
	} else {
		stm32mp_register_secure_periph_iomem(iwdg->base.pa);

		/* Expose watchdog runtime service only to secure IWDG */
		iwdg->wdt_chip.ops = &stm32_iwdg_ops;

		res = watchdog_register(&iwdg->wdt_chip);
		if (res)
			return res;
	}

	SLIST_INSERT_HEAD(&iwdg_dev_list, iwdg, link);

	return TEE_SUCCESS;
}

static TEE_Result stm32_iwdg_probe(const void *fdt, int node,
				   const void *compat_data __unused)
{
	struct stm32_iwdg_device *iwdg = NULL;
	TEE_Result res = TEE_SUCCESS;

	iwdg = calloc(1, sizeof(*iwdg));
	if (!iwdg)
		return TEE_ERROR_OUT_OF_MEMORY;

	res = stm32_iwdg_setup(iwdg, fdt, node);
	if (res)
		goto err;

	res = stm32_iwdg_register(iwdg);
	if (res)
		goto err;

	return TEE_SUCCESS;

err:
	free(iwdg);
	return res;
}

static const struct dt_device_match stm32_iwdg_match_table[] = {
	{ .compatible = "st,stm32mp1-iwdg" },
	{ }
};

DEFINE_DT_DRIVER(stm32_iwdg_dt_driver) = {
	.name = "stm32-iwdg",
	.match_table = stm32_iwdg_match_table,
	.probe = stm32_iwdg_probe,
};