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// SPDX-License-Identifier: GPL-2.0
/*
* Cadence WDT driver - Used by Xilinx Zynq
* Reference: Linux kernel Cadence watchdog driver.
*
* Author(s): Shreenidhi Shedi <yesshedi@gmail.com>
*/
#include <common.h>
#include <dm.h>
#include <wdt.h>
#include <clk.h>
#include <div64.h>
#include <linux/io.h>
DECLARE_GLOBAL_DATA_PTR;
struct cdns_regs {
u32 zmr; /* WD Zero mode register, offset - 0x0 */
u32 ccr; /* Counter Control Register offset - 0x4 */
u32 restart; /* Restart key register, offset - 0x8 */
u32 status; /* Status Register, offset - 0xC */
};
struct cdns_wdt_priv {
bool rst;
struct cdns_regs *regs;
};
#define CDNS_WDT_DEFAULT_TIMEOUT 10
/* Supports 1 - 516 sec */
#define CDNS_WDT_MIN_TIMEOUT 1
#define CDNS_WDT_MAX_TIMEOUT 516
/* Restart key */
#define CDNS_WDT_RESTART_KEY 0x00001999
/* Counter register access key */
#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000
/* Counter value divisor */
#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
/* Clock prescaler value and selection */
#define CDNS_WDT_PRESCALE_64 64
#define CDNS_WDT_PRESCALE_512 512
#define CDNS_WDT_PRESCALE_4096 4096
#define CDNS_WDT_PRESCALE_SELECT_64 1
#define CDNS_WDT_PRESCALE_SELECT_512 2
#define CDNS_WDT_PRESCALE_SELECT_4096 3
/* Input clock frequency */
#define CDNS_WDT_CLK_75MHZ 75000000
/* Counter maximum value */
#define CDNS_WDT_COUNTER_MAX 0xFFF
/********************* Register Map **********************************/
/*
* Zero Mode Register - This register controls how the time out is indicated
* and also contains the access code to allow writes to the register (0xABC).
*/
#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */
#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */
#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */
#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */
#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */
/*
* Counter Control register - This register controls how fast the timer runs
* and the reset value and also contains the access code to allow writes to
* the register.
*/
#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */
/* Write access to Registers */
static inline void cdns_wdt_writereg(u32 *addr, u32 val)
{
writel(val, addr);
}
/**
* cdns_wdt_reset - Reload the watchdog timer (i.e. pat the watchdog).
*
* @dev: Watchdog device
*
* Write the restart key value (0x00001999) to the restart register.
*
* Return: Always 0
*/
static int cdns_wdt_reset(struct udevice *dev)
{
struct cdns_wdt_priv *priv = dev_get_priv(dev);
debug("%s\n", __func__);
cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY);
return 0;
}
/**
* cdns_wdt_start - Enable and start the watchdog.
*
* @dev: Watchdog device
* @timeout: Timeout value
* @flags: Driver flags
*
* The counter value is calculated according to the formula:
* count = (timeout * clock) / prescaler + 1.
*
* The calculated count is divided by 0x1000 to obtain the field value
* to write to counter control register.
*
* Clears the contents of prescaler and counter reset value. Sets the
* prescaler to 4096 and the calculated count and access key
* to write to CCR Register.
*
* Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit)
* or Interrupt signal(IRQEN) with a specified cycles and the access
* key to write to ZMR Register.
*
* Return: Upon success 0, failure -1.
*/
static int cdns_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
{
ulong clk_f;
u32 count, prescaler, ctrl_clksel, data = 0;
struct clk clock;
struct cdns_wdt_priv *priv = dev_get_priv(dev);
if (clk_get_by_index(dev, 0, &clock) < 0) {
dev_err(dev, "failed to get clock\n");
return -1;
}
clk_f = clk_get_rate(&clock);
if (IS_ERR_VALUE(clk_f)) {
dev_err(dev, "failed to get rate\n");
return -1;
}
/* Calculate timeout in seconds and restrict to min and max value */
do_div(timeout, 1000);
timeout = max_t(u64, timeout, CDNS_WDT_MIN_TIMEOUT);
timeout = min_t(u64, timeout, CDNS_WDT_MAX_TIMEOUT);
debug("%s: CLK_FREQ %ld, timeout %lld\n", __func__, clk_f, timeout);
if (clk_f <= CDNS_WDT_CLK_75MHZ) {
prescaler = CDNS_WDT_PRESCALE_512;
ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
} else {
prescaler = CDNS_WDT_PRESCALE_4096;
ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096;
}
/*
* Counter value divisor to obtain the value of
* counter reset to be written to control register.
*/
count = (timeout * (clk_f / prescaler)) /
CDNS_WDT_COUNTER_VALUE_DIVISOR + 1;
if (count > CDNS_WDT_COUNTER_MAX)
count = CDNS_WDT_COUNTER_MAX;
cdns_wdt_writereg(&priv->regs->zmr, CDNS_WDT_ZMR_ZKEY_VAL);
count = (count << 2) & CDNS_WDT_CCR_CRV_MASK;
/* Write counter access key first to be able write to register */
data = count | CDNS_WDT_REGISTER_ACCESS_KEY | ctrl_clksel;
cdns_wdt_writereg(&priv->regs->ccr, data);
data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 |
CDNS_WDT_ZMR_ZKEY_VAL;
/* Reset on timeout if specified in device tree. */
if (priv->rst) {
data |= CDNS_WDT_ZMR_RSTEN_MASK;
data &= ~CDNS_WDT_ZMR_IRQEN_MASK;
} else {
data &= ~CDNS_WDT_ZMR_RSTEN_MASK;
data |= CDNS_WDT_ZMR_IRQEN_MASK;
}
cdns_wdt_writereg(&priv->regs->zmr, data);
cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY);
return 0;
}
/**
* cdns_wdt_stop - Stop the watchdog.
*
* @dev: Watchdog device
*
* Read the contents of the ZMR register, clear the WDEN bit in the register
* and set the access key for successful write.
*
* Return: Always 0
*/
static int cdns_wdt_stop(struct udevice *dev)
{
struct cdns_wdt_priv *priv = dev_get_priv(dev);
cdns_wdt_writereg(&priv->regs->zmr,
CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK));
return 0;
}
/**
* cdns_wdt_probe - Probe call for the device.
*
* @dev: Handle to the udevice structure.
*
* Return: Always 0.
*/
static int cdns_wdt_probe(struct udevice *dev)
{
debug("%s: Probing wdt%u\n", __func__, dev->seq);
return 0;
}
static int cdns_wdt_ofdata_to_platdata(struct udevice *dev)
{
struct cdns_wdt_priv *priv = dev_get_priv(dev);
priv->regs = (struct cdns_regs *)dev_read_addr(dev);
if (IS_ERR(priv->regs))
return PTR_ERR(priv->regs);
priv->rst = dev_read_bool(dev, "reset-on-timeout");
debug("%s: reset %d\n", __func__, priv->rst);
return 0;
}
static const struct wdt_ops cdns_wdt_ops = {
.start = cdns_wdt_start,
.reset = cdns_wdt_reset,
.stop = cdns_wdt_stop,
/* There is no bit/reg/support in IP for expire_now functionality */
};
static const struct udevice_id cdns_wdt_ids[] = {
{ .compatible = "cdns,wdt-r1p2" },
{}
};
U_BOOT_DRIVER(cdns_wdt) = {
.name = "cdns_wdt",
.id = UCLASS_WDT,
.of_match = cdns_wdt_ids,
.probe = cdns_wdt_probe,
.priv_auto_alloc_size = sizeof(struct cdns_wdt_priv),
.ofdata_to_platdata = cdns_wdt_ofdata_to_platdata,
.ops = &cdns_wdt_ops,
};