diff options
Diffstat (limited to 'drivers/clocksource/timer-econet-en751221.c')
| -rw-r--r-- | drivers/clocksource/timer-econet-en751221.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-econet-en751221.c b/drivers/clocksource/timer-econet-en751221.c new file mode 100644 index 000000000000..3b449fdaafee --- /dev/null +++ b/drivers/clocksource/timer-econet-en751221.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Timer present on EcoNet EN75xx MIPS based SoCs. + * + * Copyright (C) 2025 by Caleb James DeLisle <cjd@cjdns.fr> + */ + +#include <linux/io.h> +#include <linux/cpumask.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> +#include <linux/sched_clock.h> +#include <linux/of.h> +#include <linux/of_irq.h> +#include <linux/of_address.h> +#include <linux/cpuhotplug.h> +#include <linux/clk.h> + +#define ECONET_BITS 32 +#define ECONET_MIN_DELTA 0x00001000 +#define ECONET_MAX_DELTA GENMASK(ECONET_BITS - 2, 0) +/* 34Kc hardware has 1 block and 1004Kc has 2. */ +#define ECONET_NUM_BLOCKS DIV_ROUND_UP(NR_CPUS, 2) + +static struct { + void __iomem *membase[ECONET_NUM_BLOCKS]; + u32 freq_hz; +} econet_timer __ro_after_init; + +static DEFINE_PER_CPU(struct clock_event_device, econet_timer_pcpu); + +/* Each memory block has 2 timers, the order of registers is: + * CTL, CMR0, CNT0, CMR1, CNT1 + */ +static inline void __iomem *reg_ctl(u32 timer_n) +{ + return econet_timer.membase[timer_n >> 1]; +} + +static inline void __iomem *reg_compare(u32 timer_n) +{ + return econet_timer.membase[timer_n >> 1] + (timer_n & 1) * 0x08 + 0x04; +} + +static inline void __iomem *reg_count(u32 timer_n) +{ + return econet_timer.membase[timer_n >> 1] + (timer_n & 1) * 0x08 + 0x08; +} + +static inline u32 ctl_bit_enabled(u32 timer_n) +{ + return 1U << (timer_n & 1); +} + +static inline u32 ctl_bit_pending(u32 timer_n) +{ + return 1U << ((timer_n & 1) + 16); +} + +static bool cevt_is_pending(int cpu_id) +{ + return ioread32(reg_ctl(cpu_id)) & ctl_bit_pending(cpu_id); +} + +static irqreturn_t cevt_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *dev = this_cpu_ptr(&econet_timer_pcpu); + int cpu = cpumask_first(dev->cpumask); + + /* Each VPE has its own events, + * so this will only happen on spurious interrupt. + */ + if (!cevt_is_pending(cpu)) + return IRQ_NONE; + + iowrite32(ioread32(reg_count(cpu)), reg_compare(cpu)); + dev->event_handler(dev); + return IRQ_HANDLED; +} + +static int cevt_set_next_event(ulong delta, struct clock_event_device *dev) +{ + u32 next; + int cpu; + + cpu = cpumask_first(dev->cpumask); + next = ioread32(reg_count(cpu)) + delta; + iowrite32(next, reg_compare(cpu)); + + if ((s32)(next - ioread32(reg_count(cpu))) < ECONET_MIN_DELTA / 2) + return -ETIME; + + return 0; +} + +static int cevt_init_cpu(uint cpu) +{ + struct clock_event_device *cd = &per_cpu(econet_timer_pcpu, cpu); + u32 reg; + + pr_debug("%s: Setting up clockevent for CPU %d\n", cd->name, cpu); + + reg = ioread32(reg_ctl(cpu)) | ctl_bit_enabled(cpu); + iowrite32(reg, reg_ctl(cpu)); + + enable_percpu_irq(cd->irq, IRQ_TYPE_NONE); + + /* Do this last because it synchronously configures the timer */ + clockevents_config_and_register(cd, econet_timer.freq_hz, + ECONET_MIN_DELTA, ECONET_MAX_DELTA); + + return 0; +} + +static u64 notrace sched_clock_read(void) +{ + /* Always read from clock zero no matter the CPU */ + return (u64)ioread32(reg_count(0)); +} + +/* Init */ + +static void __init cevt_dev_init(uint cpu) +{ + iowrite32(0, reg_count(cpu)); + iowrite32(U32_MAX, reg_compare(cpu)); +} + +static int __init cevt_init(struct device_node *np) +{ + int i, irq, ret; + + irq = irq_of_parse_and_map(np, 0); + if (irq <= 0) { + pr_err("%pOFn: irq_of_parse_and_map failed", np); + return -EINVAL; + } + + ret = request_percpu_irq(irq, cevt_interrupt, np->name, &econet_timer_pcpu); + + if (ret < 0) { + pr_err("%pOFn: IRQ %d setup failed (%d)\n", np, irq, ret); + goto err_unmap_irq; + } + + for_each_possible_cpu(i) { + struct clock_event_device *cd = &per_cpu(econet_timer_pcpu, i); + + cd->rating = 310, + cd->features = CLOCK_EVT_FEAT_ONESHOT | + CLOCK_EVT_FEAT_C3STOP | + CLOCK_EVT_FEAT_PERCPU; + cd->set_next_event = cevt_set_next_event; + cd->irq = irq; + cd->cpumask = cpumask_of(i); + cd->name = np->name; + + cevt_dev_init(i); + } + + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, + "clockevents/econet/timer:starting", + cevt_init_cpu, NULL); + return 0; + +err_unmap_irq: + irq_dispose_mapping(irq); + return ret; +} + +static int __init timer_init(struct device_node *np) +{ + int num_blocks = DIV_ROUND_UP(num_possible_cpus(), 2); + struct clk *clk; + int ret; + + clk = of_clk_get(np, 0); + if (IS_ERR(clk)) { + pr_err("%pOFn: Failed to get CPU clock from DT %ld\n", np, PTR_ERR(clk)); + return PTR_ERR(clk); + } + + econet_timer.freq_hz = clk_get_rate(clk); + + for (int i = 0; i < num_blocks; i++) { + econet_timer.membase[i] = of_iomap(np, i); + if (!econet_timer.membase[i]) { + pr_err("%pOFn: failed to map register [%d]\n", np, i); + return -ENXIO; + } + } + + /* For clocksource purposes always read clock zero, whatever the CPU */ + ret = clocksource_mmio_init(reg_count(0), np->name, + econet_timer.freq_hz, 301, ECONET_BITS, + clocksource_mmio_readl_up); + if (ret) { + pr_err("%pOFn: clocksource_mmio_init failed: %d", np, ret); + return ret; + } + + ret = cevt_init(np); + if (ret < 0) + return ret; + + sched_clock_register(sched_clock_read, ECONET_BITS, + econet_timer.freq_hz); + + pr_info("%pOFn: using %u.%03u MHz high precision timer\n", np, + econet_timer.freq_hz / 1000000, + (econet_timer.freq_hz / 1000) % 1000); + + return 0; +} + +TIMER_OF_DECLARE(econet_timer_hpt, "econet,en751221-timer", timer_init); |