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268 lines
6.8 KiB
268 lines
6.8 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Cadence WDT driver - Used by Xilinx Zynq |
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* Reference: Linux kernel Cadence watchdog driver. |
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* |
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* Author(s): Shreenidhi Shedi <[email protected]> |
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*/ |
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#include <common.h> |
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#include <dm.h> |
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#include <wdt.h> |
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#include <clk.h> |
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#include <linux/io.h> |
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DECLARE_GLOBAL_DATA_PTR; |
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struct cdns_regs { |
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u32 zmr; /* WD Zero mode register, offset - 0x0 */ |
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u32 ccr; /* Counter Control Register offset - 0x4 */ |
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u32 restart; /* Restart key register, offset - 0x8 */ |
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u32 status; /* Status Register, offset - 0xC */ |
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}; |
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struct cdns_wdt_priv { |
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bool rst; |
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u32 timeout; |
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struct cdns_regs *regs; |
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}; |
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#define CDNS_WDT_DEFAULT_TIMEOUT 10 |
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/* Supports 1 - 516 sec */ |
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#define CDNS_WDT_MIN_TIMEOUT 1 |
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#define CDNS_WDT_MAX_TIMEOUT 516 |
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/* Restart key */ |
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#define CDNS_WDT_RESTART_KEY 0x00001999 |
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/* Counter register access key */ |
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#define CDNS_WDT_REGISTER_ACCESS_KEY 0x00920000 |
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/* Counter value divisor */ |
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#define CDNS_WDT_COUNTER_VALUE_DIVISOR 0x1000 |
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/* Clock prescaler value and selection */ |
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#define CDNS_WDT_PRESCALE_64 64 |
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#define CDNS_WDT_PRESCALE_512 512 |
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#define CDNS_WDT_PRESCALE_4096 4096 |
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#define CDNS_WDT_PRESCALE_SELECT_64 1 |
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#define CDNS_WDT_PRESCALE_SELECT_512 2 |
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#define CDNS_WDT_PRESCALE_SELECT_4096 3 |
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/* Input clock frequency */ |
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#define CDNS_WDT_CLK_75MHZ 75000000 |
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/* Counter maximum value */ |
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#define CDNS_WDT_COUNTER_MAX 0xFFF |
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/********************* Register Map **********************************/ |
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/* |
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* Zero Mode Register - This register controls how the time out is indicated |
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* and also contains the access code to allow writes to the register (0xABC). |
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*/ |
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#define CDNS_WDT_ZMR_WDEN_MASK 0x00000001 /* Enable the WDT */ |
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#define CDNS_WDT_ZMR_RSTEN_MASK 0x00000002 /* Enable the reset output */ |
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#define CDNS_WDT_ZMR_IRQEN_MASK 0x00000004 /* Enable IRQ output */ |
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#define CDNS_WDT_ZMR_RSTLEN_16 0x00000030 /* Reset pulse of 16 pclk cycles */ |
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#define CDNS_WDT_ZMR_ZKEY_VAL 0x00ABC000 /* Access key, 0xABC << 12 */ |
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/* |
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* Counter Control register - This register controls how fast the timer runs |
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* and the reset value and also contains the access code to allow writes to |
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* the register. |
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*/ |
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#define CDNS_WDT_CCR_CRV_MASK 0x00003FFC /* Counter reset value */ |
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/* Write access to Registers */ |
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static inline void cdns_wdt_writereg(u32 *addr, u32 val) |
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{ |
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writel(val, addr); |
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} |
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/** |
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* cdns_wdt_reset - Reload the watchdog timer (i.e. pat the watchdog). |
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* |
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* @dev: Watchdog device |
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* |
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* Write the restart key value (0x00001999) to the restart register. |
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* |
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* Return: Always 0 |
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*/ |
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static int cdns_wdt_reset(struct udevice *dev) |
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{ |
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struct cdns_wdt_priv *priv = dev_get_priv(dev); |
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debug("%s\n", __func__); |
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cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY); |
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return 0; |
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} |
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/** |
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* cdns_wdt_start - Enable and start the watchdog. |
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* |
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* @dev: Watchdog device |
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* @timeout: Timeout value |
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* @flags: Driver flags |
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* |
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* The counter value is calculated according to the formula: |
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* count = (timeout * clock) / prescaler + 1. |
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* |
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* The calculated count is divided by 0x1000 to obtain the field value |
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* to write to counter control register. |
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* |
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* Clears the contents of prescaler and counter reset value. Sets the |
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* prescaler to 4096 and the calculated count and access key |
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* to write to CCR Register. |
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* |
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* Sets the WDT (WDEN bit) and either the Reset signal(RSTEN bit) |
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* or Interrupt signal(IRQEN) with a specified cycles and the access |
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* key to write to ZMR Register. |
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* |
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* Return: Upon success 0, failure -1. |
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*/ |
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static int cdns_wdt_start(struct udevice *dev, u64 timeout, ulong flags) |
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{ |
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ulong clk_f; |
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u32 count, prescaler, ctrl_clksel, data = 0; |
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struct clk clock; |
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struct cdns_wdt_priv *priv = dev_get_priv(dev); |
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if (clk_get_by_index(dev, 0, &clock) < 0) { |
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dev_err(dev, "failed to get clock\n"); |
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return -1; |
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} |
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clk_f = clk_get_rate(&clock); |
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if (IS_ERR_VALUE(clk_f)) { |
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dev_err(dev, "failed to get rate\n"); |
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return -1; |
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} |
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if ((timeout < CDNS_WDT_MIN_TIMEOUT) || |
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(timeout > CDNS_WDT_MAX_TIMEOUT)) { |
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timeout = priv->timeout; |
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} |
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debug("%s: CLK_FREQ %ld, timeout %lld\n", __func__, clk_f, timeout); |
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if (clk_f <= CDNS_WDT_CLK_75MHZ) { |
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prescaler = CDNS_WDT_PRESCALE_512; |
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ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_512; |
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} else { |
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prescaler = CDNS_WDT_PRESCALE_4096; |
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ctrl_clksel = CDNS_WDT_PRESCALE_SELECT_4096; |
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} |
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/* |
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* Counter value divisor to obtain the value of |
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* counter reset to be written to control register. |
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*/ |
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count = (timeout * (clk_f / prescaler)) / |
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CDNS_WDT_COUNTER_VALUE_DIVISOR + 1; |
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if (count > CDNS_WDT_COUNTER_MAX) |
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count = CDNS_WDT_COUNTER_MAX; |
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cdns_wdt_writereg(&priv->regs->zmr, CDNS_WDT_ZMR_ZKEY_VAL); |
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count = (count << 2) & CDNS_WDT_CCR_CRV_MASK; |
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/* Write counter access key first to be able write to register */ |
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data = count | CDNS_WDT_REGISTER_ACCESS_KEY | ctrl_clksel; |
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cdns_wdt_writereg(&priv->regs->ccr, data); |
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data = CDNS_WDT_ZMR_WDEN_MASK | CDNS_WDT_ZMR_RSTLEN_16 | |
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CDNS_WDT_ZMR_ZKEY_VAL; |
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/* Reset on timeout if specified in device tree. */ |
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if (priv->rst) { |
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data |= CDNS_WDT_ZMR_RSTEN_MASK; |
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data &= ~CDNS_WDT_ZMR_IRQEN_MASK; |
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} else { |
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data &= ~CDNS_WDT_ZMR_RSTEN_MASK; |
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data |= CDNS_WDT_ZMR_IRQEN_MASK; |
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} |
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cdns_wdt_writereg(&priv->regs->zmr, data); |
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cdns_wdt_writereg(&priv->regs->restart, CDNS_WDT_RESTART_KEY); |
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return 0; |
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} |
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/** |
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* cdns_wdt_stop - Stop the watchdog. |
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* |
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* @dev: Watchdog device |
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* |
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* Read the contents of the ZMR register, clear the WDEN bit in the register |
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* and set the access key for successful write. |
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* |
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* Return: Always 0 |
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*/ |
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static int cdns_wdt_stop(struct udevice *dev) |
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{ |
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struct cdns_wdt_priv *priv = dev_get_priv(dev); |
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cdns_wdt_writereg(&priv->regs->zmr, |
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CDNS_WDT_ZMR_ZKEY_VAL & (~CDNS_WDT_ZMR_WDEN_MASK)); |
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return 0; |
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} |
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/** |
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* cdns_wdt_probe - Probe call for the device. |
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* |
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* @dev: Handle to the udevice structure. |
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* |
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* Return: Always 0. |
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*/ |
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static int cdns_wdt_probe(struct udevice *dev) |
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{ |
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debug("%s: Probing wdt%u\n", __func__, dev->seq); |
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return 0; |
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} |
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static int cdns_wdt_ofdata_to_platdata(struct udevice *dev) |
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{ |
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struct cdns_wdt_priv *priv = dev_get_priv(dev); |
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priv->regs = (struct cdns_regs *)dev_read_addr(dev); |
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if (IS_ERR(priv->regs)) |
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return PTR_ERR(priv->regs); |
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priv->timeout = dev_read_u32_default(dev, "timeout-sec", |
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CDNS_WDT_DEFAULT_TIMEOUT); |
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priv->rst = dev_read_bool(dev, "reset-on-timeout"); |
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debug("%s: timeout %d, reset %d\n", __func__, priv->timeout, priv->rst); |
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return 0; |
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} |
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static const struct wdt_ops cdns_wdt_ops = { |
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.start = cdns_wdt_start, |
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.reset = cdns_wdt_reset, |
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.stop = cdns_wdt_stop, |
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/* There is no bit/reg/support in IP for expire_now functionality */ |
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}; |
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static const struct udevice_id cdns_wdt_ids[] = { |
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{ .compatible = "cdns,wdt-r1p2" }, |
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{} |
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}; |
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U_BOOT_DRIVER(cdns_wdt) = { |
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.name = "cdns_wdt", |
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.id = UCLASS_WDT, |
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.of_match = cdns_wdt_ids, |
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.probe = cdns_wdt_probe, |
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.priv_auto_alloc_size = sizeof(struct cdns_wdt_priv), |
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.ofdata_to_platdata = cdns_wdt_ofdata_to_platdata, |
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.ops = &cdns_wdt_ops, |
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};
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