1 // SPDX-License-Identifier: GPL-2.0
3 * Cadence WDT driver - Used by Xilinx Zynq
4 * Reference: Linux kernel Cadence watchdog driver.
6 * Author(s): Shreenidhi Shedi <yesshedi@gmail.com>
14 #include <dm/device_compat.h>
15 #include <linux/err.h>
18 DECLARE_GLOBAL_DATA_PTR;
21 u32 zmr; /* WD Zero mode register, offset - 0x0 */
22 u32 ccr; /* Counter Control Register offset - 0x4 */
23 u32 restart; /* Restart key register, offset - 0x8 */
24 u32 status; /* Status Register, offset - 0xC */
27 struct cdns_wdt_priv {
29 struct cdns_regs *regs;
32 #define CDNS_WDT_DEFAULT_TIMEOUT 10
34 /* Supports 1 - 516 sec */
35 #define CDNS_WDT_MIN_TIMEOUT 1
36 #define CDNS_WDT_MAX_TIMEOUT 516
39 #define CDNS_WDT_RESTART_KEY 0x00001999
41 /* Counter register access key */
42 #define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000
44 /* Counter value divisor */
45 #define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000
47 /* Clock prescaler value and selection */
48 #define CDNS_WDT_PRESCALE_64 64
49 #define CDNS_WDT_PRESCALE_512 512
50 #define CDNS_WDT_PRESCALE_4096 4096
51 #define CDNS_WDT_PRESCALE_SELECT_64 1
52 #define CDNS_WDT_PRESCALE_SELECT_512 2
53 #define CDNS_WDT_PRESCALE_SELECT_4096 3
55 /* Input clock frequency */
56 #define CDNS_WDT_CLK_75MHZ 75000000
58 /* Counter maximum value */
59 #define CDNS_WDT_COUNTER_MAX 0xFFF
61 /********************* Register Map **********************************/
64 * Zero Mode Register - This register controls how the time out is indicated
65 * and also contains the access code to allow writes to the register (0xABC).
67 #define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */
68 #define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */
69 #define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */
70 #define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */
71 #define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */
74 * Counter Control register - This register controls how fast the timer runs
75 * and the reset value and also contains the access code to allow writes to
78 #define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */
80 /* Write access to Registers */
81 static inline void cdns_wdt_writereg(u32 *addr, u32 val)
87 * cdns_wdt_reset - Reload the watchdog timer (i.e. pat the watchdog).
89 * @dev: Watchdog device
91 * Write the restart key value (0x00001999) to the restart register.
95 static int cdns_wdt_reset(struct udevice *dev)
97 struct cdns_wdt_priv *priv = dev_get_priv(dev);
99 debug("%s\n", __func__);
101 cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY);
107 * cdns_wdt_start - Enable and start the watchdog.
109 * @dev: Watchdog device
110 * @timeout: Timeout value
111 * @flags: Driver flags
113 * The counter value is calculated according to the formula:
114 * count = (timeout * clock) / prescaler + 1.
116 * The calculated count is divided by 0x1000 to obtain the field value
117 * to write to counter control register.
119 * Clears the contents of prescaler and counter reset value. Sets the
120 * prescaler to 4096 and the calculated count and access key
121 * to write to CCR Register.
123 * Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit)
124 * or Interrupt signal(IRQEN) with a specified cycles and the access
125 * key to write to ZMR Register.
127 * Return: Upon success 0, failure -1.
129 static int cdns_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
132 u32 count, prescaler, ctrl_clksel, data = 0;
134 struct cdns_wdt_priv *priv = dev_get_priv(dev);
136 if (clk_get_by_index(dev, 0, &clock) < 0) {
137 dev_err(dev, "failed to get clock\n");
141 clk_f = clk_get_rate(&clock);
142 if (IS_ERR_VALUE(clk_f)) {
143 dev_err(dev, "failed to get rate\n");
147 /* Calculate timeout in seconds and restrict to min and max value */
148 do_div(timeout, 1000);
149 timeout = max_t(u64, timeout, CDNS_WDT_MIN_TIMEOUT);
150 timeout = min_t(u64, timeout, CDNS_WDT_MAX_TIMEOUT);
152 debug("%s: CLK_FREQ %ld, timeout %lld\n", __func__, clk_f, timeout);
154 if (clk_f <= CDNS_WDT_CLK_75MHZ) {
155 prescaler = CDNS_WDT_PRESCALE_512;
156 ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512;
158 prescaler = CDNS_WDT_PRESCALE_4096;
159 ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096;
163 * Counter value divisor to obtain the value of
164 * counter reset to be written to control register.
166 count = (timeout * (clk_f / prescaler)) /
167 CDNS_WDT_COUNTER_VALUE_DIVISOR + 1;
169 if (count > CDNS_WDT_COUNTER_MAX)
170 count = CDNS_WDT_COUNTER_MAX;
172 cdns_wdt_writereg(&priv->regs->zmr, CDNS_WDT_ZMR_ZKEY_VAL);
174 count = (count << 2) & CDNS_WDT_CCR_CRV_MASK;
176 /* Write counter access key first to be able write to register */
177 data = count | CDNS_WDT_REGISTER_ACCESS_KEY | ctrl_clksel;
178 cdns_wdt_writereg(&priv->regs->ccr, data);
180 data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 |
181 CDNS_WDT_ZMR_ZKEY_VAL;
183 /* Reset on timeout if specified in device tree. */
185 data |= CDNS_WDT_ZMR_RSTEN_MASK;
186 data &= ~CDNS_WDT_ZMR_IRQEN_MASK;
188 data &= ~CDNS_WDT_ZMR_RSTEN_MASK;
189 data |= CDNS_WDT_ZMR_IRQEN_MASK;
192 cdns_wdt_writereg(&priv->regs->zmr, data);
193 cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY);
199 * cdns_wdt_stop - Stop the watchdog.
201 * @dev: Watchdog device
203 * Read the contents of the ZMR register, clear the WDEN bit in the register
204 * and set the access key for successful write.
208 static int cdns_wdt_stop(struct udevice *dev)
210 struct cdns_wdt_priv *priv = dev_get_priv(dev);
212 cdns_wdt_writereg(&priv->regs->zmr,
213 CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK));
219 * cdns_wdt_probe - Probe call for the device.
221 * @dev: Handle to the udevice structure.
225 static int cdns_wdt_probe(struct udevice *dev)
227 debug("%s: Probing wdt%u\n", __func__, dev->seq);
232 static int cdns_wdt_ofdata_to_platdata(struct udevice *dev)
234 struct cdns_wdt_priv *priv = dev_get_priv(dev);
236 priv->regs = (struct cdns_regs *)dev_read_addr(dev);
237 if (IS_ERR(priv->regs))
238 return PTR_ERR(priv->regs);
240 priv->rst = dev_read_bool(dev, "reset-on-timeout");
242 debug("%s: reset %d\n", __func__, priv->rst);
247 static const struct wdt_ops cdns_wdt_ops = {
248 .start = cdns_wdt_start,
249 .reset = cdns_wdt_reset,
250 .stop = cdns_wdt_stop,
251 /* There is no bit/reg/support in IP for expire_now functionality */
254 static const struct udevice_id cdns_wdt_ids[] = {
255 { .compatible = "cdns,wdt-r1p2" },
259 U_BOOT_DRIVER(cdns_wdt) = {
262 .of_match = cdns_wdt_ids,
263 .probe = cdns_wdt_probe,
264 .priv_auto_alloc_size = sizeof(struct cdns_wdt_priv),
265 .ofdata_to_platdata = cdns_wdt_ofdata_to_platdata,
266 .ops = &cdns_wdt_ops,