drivers/clocksource/timer-gxp.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
0003
0004 #include <linux/clk.h>
0005 #include <linux/clockchips.h>
0006 #include <linux/clocksource.h>
0007 #include <linux/interrupt.h>
0008 #include <linux/of_address.h>
0009 #include <linux/of_irq.h>
0010 #include <linux/of_platform.h>
0011 #include <linux/sched_clock.h>
0012
0013 #define TIMER0_FREQ 1000000
0014 #define GXP_TIMER_CNT_OFS 0x00
0015 #define GXP_TIMESTAMP_OFS 0x08
0016 #define GXP_TIMER_CTRL_OFS 0x14
0017
0018 /* TCS Stands for Timer Control/Status: these are masks to be used in */
0019 /* the Timer Count Registers */
0020 #define MASK_TCS_ENABLE 0x01
0021 #define MASK_TCS_PERIOD 0x02
0022 #define MASK_TCS_RELOAD 0x04
0023 #define MASK_TCS_TC 0x80
0024
0025 struct gxp_timer {
0026     void __iomem *counter;
0027     void __iomem *control;
0028     struct clock_event_device evt;
0029 };
0030
0031 static struct gxp_timer *gxp_timer;
0032
0033 static void __iomem *system_clock __ro_after_init;
0034
0035 static inline struct gxp_timer *to_gxp_timer(struct clock_event_device *evt_dev)
0036 {
0037     return container_of(evt_dev, struct gxp_timer, evt);
0038 }
0039
0040 static u64 notrace gxp_sched_read(void)
0041 {
0042     return readl_relaxed(system_clock);
0043 }
0044
0045 static int gxp_time_set_next_event(unsigned long event, struct clock_event_device *evt_dev)
0046 {
0047     struct gxp_timer *timer = to_gxp_timer(evt_dev);
0048
0049     /* Stop counting and disable interrupt before updating */
0050     writeb_relaxed(MASK_TCS_TC, timer->control);
0051     writel_relaxed(event, timer->counter);
0052     writeb_relaxed(MASK_TCS_TC | MASK_TCS_ENABLE, timer->control);
0053
0054     return 0;
0055 }
0056
0057 static irqreturn_t gxp_timer_interrupt(int irq, void *dev_id)
0058 {
0059     struct gxp_timer *timer = (struct gxp_timer *)dev_id;
0060
0061     if (!(readb_relaxed(timer->control) & MASK_TCS_TC))
0062         return IRQ_NONE;
0063
0064     writeb_relaxed(MASK_TCS_TC, timer->control);
0065
0066     timer->evt.event_handler(&timer->evt);
0067
0068     return IRQ_HANDLED;
0069 }
0070
0071 static int __init gxp_timer_init(struct device_node *node)
0072 {
0073     void __iomem *base;
0074     struct clk *clk;
0075     u32 freq;
0076     int ret, irq;
0077
0078     gxp_timer = kzalloc(sizeof(*gxp_timer), GFP_KERNEL);
0079     if (!gxp_timer) {
0080         ret = -ENOMEM;
0081         pr_err("Can't allocate gxp_timer");
0082         return ret;
0083     }
0084
0085     clk = of_clk_get(node, 0);
0086     if (IS_ERR(clk)) {
0087         ret = (int)PTR_ERR(clk);
0088         pr_err("%pOFn clock not found: %d\n", node, ret);
0089         goto err_free;
0090     }
0091
0092     ret = clk_prepare_enable(clk);
0093     if (ret) {
0094         pr_err("%pOFn clock enable failed: %d\n", node, ret);
0095         goto err_clk_enable;
0096     }
0097
0098     base = of_iomap(node, 0);
0099     if (!base) {
0100         ret = -ENXIO;
0101         pr_err("Can't map timer base registers");
0102         goto err_iomap;
0103     }
0104
0105     /* Set the offsets to the clock register and timer registers */
0106     gxp_timer->counter = base + GXP_TIMER_CNT_OFS;
0107     gxp_timer->control = base + GXP_TIMER_CTRL_OFS;
0108     system_clock = base + GXP_TIMESTAMP_OFS;
0109
0110     gxp_timer->evt.name = node->name;
0111     gxp_timer->evt.rating = 300;
0112     gxp_timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
0113     gxp_timer->evt.set_next_event = gxp_time_set_next_event;
0114     gxp_timer->evt.cpumask = cpumask_of(0);
0115
0116     irq = irq_of_parse_and_map(node, 0);
0117     if (irq <= 0) {
0118         ret = -EINVAL;
0119         pr_err("GXP Timer Can't parse IRQ %d", irq);
0120         goto err_exit;
0121     }
0122
0123     freq = clk_get_rate(clk);
0124
0125     ret = clocksource_mmio_init(system_clock, node->name, freq,
0126                     300, 32, clocksource_mmio_readl_up);
0127     if (ret) {
0128         pr_err("%pOFn init clocksource failed: %d", node, ret);
0129         goto err_exit;
0130     }
0131
0132     sched_clock_register(gxp_sched_read, 32, freq);
0133
0134     irq = irq_of_parse_and_map(node, 0);
0135     if (irq <= 0) {
0136         ret = -EINVAL;
0137         pr_err("%pOFn Can't parse IRQ %d", node, irq);
0138         goto err_exit;
0139     }
0140
0141     clockevents_config_and_register(&gxp_timer->evt, TIMER0_FREQ,
0142                     0xf, 0xffffffff);
0143
0144     ret = request_irq(irq, gxp_timer_interrupt, IRQF_TIMER | IRQF_SHARED,
0145               node->name, gxp_timer);
0146     if (ret) {
0147         pr_err("%pOFn request_irq() failed: %d", node, ret);
0148         goto err_exit;
0149     }
0150
0151     pr_debug("gxp: system timer (irq = %d)\n", irq);
0152     return 0;
0153
0154 err_exit:
0155     iounmap(base);
0156 err_iomap:
0157     clk_disable_unprepare(clk);
0158 err_clk_enable:
0159     clk_put(clk);
0160 err_free:
0161     kfree(gxp_timer);
0162     return ret;
0163 }
0164
0165 /*
0166  * This probe gets called after the timer is already up and running. This will create
0167  * the watchdog device as a child since the registers are shared.
0168  */
0169
0170 static int gxp_timer_probe(struct platform_device *pdev)
0171 {
0172     struct platform_device *gxp_watchdog_device;
0173     struct device *dev = &pdev->dev;
0174
0175     if (!gxp_timer) {
0176         pr_err("Gxp Timer not initialized, cannot create watchdog");
0177         return -ENOMEM;
0178     }
0179
0180     gxp_watchdog_device = platform_device_alloc("gxp-wdt", -1);
0181     if (!gxp_watchdog_device) {
0182         pr_err("Timer failed to allocate gxp-wdt");
0183         return -ENOMEM;
0184     }
0185
0186     /* Pass the base address (counter) as platform data and nothing else */
0187     gxp_watchdog_device->dev.platform_data = gxp_timer->counter;
0188     gxp_watchdog_device->dev.parent = dev;
0189
0190     return platform_device_add(gxp_watchdog_device);
0191 }
0192
0193 static const struct of_device_id gxp_timer_of_match[] = {
0194     { .compatible = "hpe,gxp-timer", },
0195     {},
0196 };
0197
0198 static struct platform_driver gxp_timer_driver = {
0199     .probe  = gxp_timer_probe,
0200     .driver = {
0201         .name = "gxp-timer",
0202         .of_match_table = gxp_timer_of_match,
0203         .suppress_bind_attrs = true,
0204     },
0205 };
0206
0207 builtin_platform_driver(gxp_timer_driver);
0208
0209 TIMER_OF_DECLARE(gxp, "hpe,gxp-timer", gxp_timer_init);