[PATCH v4 2/7] clocksource/drivers: Add EcoNet Timer HPT driver
Caleb James DeLisle
cjd at cjdns.fr
Mon May 5 11:09:47 PDT 2025
On 05/05/2025 18:36, Daniel Lezcano wrote:
> On Wed, Apr 30, 2025 at 01:34:28PM +0000, Caleb James DeLisle wrote:
>> Introduce a clocksource driver for the so-called high-precision timer (HPT)
>> in the EcoNet EN751221 MIPS SoC.
> As a new driver, please document the timer (up - down ?, SPI/PPI, etc
> ...) that will help to understand the code more easily, especially the
> reg_* functions (purposes?).
Sure thing, I can elaborate the comment in the header of
timer-econet-en751221.c. Let me know if you'd like it described
somewhere else as well, such as the help of config ECONET_EN751221_TIMER.
>
>> Signed-off-by: Caleb James DeLisle <cjd at cjdns.fr>
>> ---
>> drivers/clocksource/Kconfig | 8 +
>> drivers/clocksource/Makefile | 1 +
>> drivers/clocksource/timer-econet-en751221.c | 216 ++++++++++++++++++++
>> 3 files changed, 225 insertions(+)
>> create mode 100644 drivers/clocksource/timer-econet-en751221.c
>>
>> diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>> index 487c85259967..976afb0b2312 100644
>> --- a/drivers/clocksource/Kconfig
>> +++ b/drivers/clocksource/Kconfig
>> @@ -73,6 +73,14 @@ config DW_APB_TIMER_OF
>> select DW_APB_TIMER
>> select TIMER_OF
>>
>> +config ECONET_EN751221_TIMER
>> + bool "EcoNet EN751221 High Precision Timer" if COMPILE_TEST
>> + depends on HAS_IOMEM
>> + select CLKSRC_MMIO
>> + select TIMER_OF
>> + help
>> + Support for CPU timer found on EcoNet MIPS based SoCs.
>> +
>> config FTTMR010_TIMER
>> bool "Faraday Technology timer driver" if COMPILE_TEST
>> depends on HAS_IOMEM
>> diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile
>> index 43ef16a4efa6..d2998601eda5 100644
>> --- a/drivers/clocksource/Makefile
>> +++ b/drivers/clocksource/Makefile
>> @@ -17,6 +17,7 @@ obj-$(CONFIG_CLKBLD_I8253) += i8253.o
>> obj-$(CONFIG_CLKSRC_MMIO) += mmio.o
>> obj-$(CONFIG_DAVINCI_TIMER) += timer-davinci.o
>> obj-$(CONFIG_DIGICOLOR_TIMER) += timer-digicolor.o
>> +obj-$(CONFIG_ECONET_EN751221_TIMER) += timer-econet-en751221.o
>> obj-$(CONFIG_OMAP_DM_TIMER) += timer-ti-dm.o
>> obj-$(CONFIG_OMAP_DM_SYSTIMER) += timer-ti-dm-systimer.o
>> obj-$(CONFIG_DW_APB_TIMER) += dw_apb_timer.o
>> diff --git a/drivers/clocksource/timer-econet-en751221.c b/drivers/clocksource/timer-econet-en751221.c
>> new file mode 100644
>> index 000000000000..9cfeead09377
>> --- /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 at 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);
>> +
>> + if (!cevt_is_pending(cpu)) {
>> + pr_debug("%s IRQ %d on CPU %d is not pending\n", __func__, irq, cpu);
>> + return IRQ_NONE;
>> + }
> How this can happen ? Can this interrupt be shared ?
To my knowledge it can't, but vendor code does it and I wasn't feeling
bold enough to gamble.
> The system will account this as a spurious interrupt, the debug
> message is not needed.
Good point, will remove.
>
>> + 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_info("%s: Setting up clockevent for CPU %d\n", cd->name, cpu);
> That is more debug information
Fair enough, will change.
>> + 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_MIPS_GIC_TIMER_STARTING,
>> + "clockevents/en75/timer:starting",
>> + cevt_init_cpu, NULL);
> cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, ... ) ?
I see that Ingenic does this. This is the only timer so until it's up,
sleeping causes a hang. If sleeping is prior to CPUHP_AP_ONLINE_DYN is
considered a bug then this should be okay, but I'm not informed enough
to say whether that is the case so I'll follow your guidance here.
Thanks,
Caleb
>
>> + 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);
>> --
>> 2.39.5
>>
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