u-boot/drivers/watchdog/cdns_wdt.c
Simon Glass 8b85dfc675 dm: Avoid accessing seq directly
At present various drivers etc. access the device's 'seq' member directly.
This makes it harder to change the meaning of that member. Change access
to go through a function instead.

The drivers/i2c/lpc32xx_i2c.c file is left unchanged for now.

Signed-off-by: Simon Glass <sjg@chromium.org>
2020-12-18 20:32:21 -07:00

266 lines
6.8 KiB
C

// 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 <log.h>
#include <wdt.h>
#include <clk.h>
#include <div64.h>
#include <dm/device_compat.h>
#include <linux/err.h>
#include <linux/io.h>
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(dev));
return 0;
}
static int cdns_wdt_of_to_plat(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 = sizeof(struct cdns_wdt_priv),
.of_to_plat = cdns_wdt_of_to_plat,
.ops = &cdns_wdt_ops,
};