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bh=ROGDfW/sOKRuVITcXBG6WpnxRQy78vMNrySdIALy/lI=; b=Tev7glSVV8v9PTBtXq0t4aa8OQxGsjTCTGk2+5iky3lj6djovqiMpv8KBnCUIfJsV4 36r4DM8DkwhedFpo+iYnUV966T0EhKgJuU8qEtqaVVFMVr6faBpF+iB8S2YVNoJvNhO1 5yCLpfJSLkCWf96M4n2oFTNwCBZZ+zNA1g1nJ+ue9lx3fdvs+1kvUPawkSJyNxkmupZr p6Wecac180FEcjlYcy7lCJBXYIs4gG155i9cUfXkft8srDVOH/gQNxUhNII6a2WHNyq2 L0SMscGYl3kvmQmBKRCb04Icl+Nh/+r2mhVByY2u0T1+94m6LnK7y1/vBUlHFJ2Psh9g iw8A== X-Gm-Message-State: AOAM531a960xq4RJVihCw6j4yekvw2aM42A+mbns872pyqOBjn75RB7d i5aMVUud404s8VPGIU/qszWnpmtISfHfRFifR+sD X-Google-Smtp-Source: ABdhPJxyAn1vQoGf/buvBDraXct4LF9Xdi+8G+j/HHs1UTu85DhtfEaDBlAL/3+WgcaqfxRA+C7xSsuoMv5uPtSGmIw= X-Received: by 2002:a1c:7c19:: with SMTP id x25mr5263186wmc.176.1595360373924; Tue, 21 Jul 2020 12:39:33 -0700 (PDT) MIME-Version: 1.0 References: <20200717075101.263332-1-anup.patel@wdc.com> <20200717075101.263332-3-anup.patel@wdc.com> In-Reply-To: From: Atish Patra Date: Tue, 21 Jul 2020 12:39:22 -0700 Message-ID: Subject: Re: [PATCH v4 2/4] clocksource/drivers: Add CLINT timer driver To: Anup Patel X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200721_153935_363007_E8DEC11C X-CRM114-Status: GOOD ( 40.80 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devicetree@vger.kernel.org, Damien Le Moal , Daniel Lezcano , Emil Renner Berhing , Anup Patel , "linux-kernel@vger.kernel.org List" , Atish Patra , Rob Herring , Palmer Dabbelt , Paul Walmsley , Alistair Francis , Thomas Gleixner , linux-riscv , Albert Ou Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On Tue, Jul 21, 2020 at 4:44 AM Anup Patel wrote: > > On Tue, Jul 21, 2020 at 6:41 AM Atish Patra wrote: > > > > On Fri, Jul 17, 2020 at 12:52 AM Anup Patel wrote: > > > > > > We add a separate CLINT timer driver for Linux RISC-V M-mode (i.e. > > > RISC-V NoMMU kernel). > > > > > > The CLINT MMIO device provides three things: > > > 1. 64bit free running counter register > > > 2. 64bit per-CPU time compare registers > > > 3. 32bit per-CPU inter-processor interrupt registers > > > > > > Unlike other timer devices, CLINT provides IPI registers along with > > > timer registers. To use CLINT IPI registers, the CLINT timer driver > > > provides IPI related callbacks to arch/riscv. > > > > > > Signed-off-by: Anup Patel > > > Tested-by: Emil Renner Berhing > > > --- > > > drivers/clocksource/Kconfig | 9 ++ > > > drivers/clocksource/Makefile | 1 + > > > drivers/clocksource/timer-clint.c | 231 ++++++++++++++++++++++++++++++ > > > include/linux/cpuhotplug.h | 1 + > > > 4 files changed, 242 insertions(+) > > > create mode 100644 drivers/clocksource/timer-clint.c > > > > > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > > > index 91418381fcd4..e1ce0d510a03 100644 > > > --- a/drivers/clocksource/Kconfig > > > +++ b/drivers/clocksource/Kconfig > > > @@ -658,6 +658,15 @@ config RISCV_TIMER > > > is accessed via both the SBI and the rdcycle instruction. This is > > > required for all RISC-V systems. > > > > > > +config CLINT_TIMER > > > + bool "Timer for the RISC-V platform" > > > + depends on GENERIC_SCHED_CLOCK && RISCV_M_MODE > > > + select TIMER_PROBE > > > + select TIMER_OF > > > + help > > > + This option enables the CLINT timer for RISC-V systems. The CLINT > > > + driver is usually used for NoMMU RISC-V systems. > > > + > > > config CSKY_MP_TIMER > > > bool "SMP Timer for the C-SKY platform" if COMPILE_TEST > > > depends on CSKY > > > diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile > > > index bdda1a2e4097..18e700e703a0 100644 > > > --- a/drivers/clocksource/Makefile > > > +++ b/drivers/clocksource/Makefile > > > @@ -87,6 +87,7 @@ obj-$(CONFIG_CLKSRC_ST_LPC) += clksrc_st_lpc.o > > > obj-$(CONFIG_X86_NUMACHIP) += numachip.o > > > obj-$(CONFIG_ATCPIT100_TIMER) += timer-atcpit100.o > > > obj-$(CONFIG_RISCV_TIMER) += timer-riscv.o > > > +obj-$(CONFIG_CLINT_TIMER) += timer-clint.o > > > obj-$(CONFIG_CSKY_MP_TIMER) += timer-mp-csky.o > > > obj-$(CONFIG_GX6605S_TIMER) += timer-gx6605s.o > > > obj-$(CONFIG_HYPERV_TIMER) += hyperv_timer.o > > > diff --git a/drivers/clocksource/timer-clint.c b/drivers/clocksource/timer-clint.c > > > new file mode 100644 > > > index 000000000000..e1698efa73a1 > > > --- /dev/null > > > +++ b/drivers/clocksource/timer-clint.c > > > @@ -0,0 +1,231 @@ > > > +// SPDX-License-Identifier: GPL-2.0 > > > +/* > > > + * Copyright (C) 2020 Western Digital Corporation or its affiliates. > > > + * > > > + * Most of the M-mode (i.e. NoMMU) RISC-V systems usually have a > > > + * CLINT MMIO timer device. > > > + */ > > > + > > > +#define pr_fmt(fmt) "clint: " fmt > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > +#include > > > + > > > +#define CLINT_IPI_OFF 0 > > > +#define CLINT_TIMER_CMP_OFF 0x4000 > > > +#define CLINT_TIMER_VAL_OFF 0xbff8 > > > + > > > +/* CLINT manages IPI and Timer for RISC-V M-mode */ > > > +static u32 __iomem *clint_ipi_base; > > > +static u64 __iomem *clint_timer_cmp; > > > +static u64 __iomem *clint_timer_val; > > > +static unsigned long clint_timer_freq; > > > +static unsigned int clint_timer_irq; > > > + > > > +static void clint_send_ipi(const struct cpumask *target) > > > +{ > > > + unsigned int cpu; > > > + > > > + for_each_cpu(cpu, target) > > > + writel(1, clint_ipi_base + cpuid_to_hartid_map(cpu)); > > > +} > > > + > > > +static void clint_clear_ipi(void) > > > +{ > > > + writel(0, clint_ipi_base + cpuid_to_hartid_map(smp_processor_id())); > > > +} > > > + > > > +static struct riscv_ipi_ops clint_ipi_ops = { > > > + .ipi_inject = clint_send_ipi, > > > + .ipi_clear = clint_clear_ipi, > > > +}; > > > + > > > +#ifdef CONFIG_64BIT > > > +#define clint_get_cycles() readq_relaxed(clint_timer_val) > > > +#else > > > +#define clint_get_cycles() readl_relaxed(clint_timer_val) > > > +#define clint_get_cycles_hi() readl_relaxed(((u32 *)clint_timer_val) + 1) > > > +#endif > > > + > > > +#ifdef CONFIG_64BIT > > > +static u64 notrace clint_get_cycles64(void) > > > +{ > > > + return clint_get_cycles(); > > > +} > > > +#else /* CONFIG_64BIT */ > > > +static u64 notrace clint_get_cycles64(void) > > > +{ > > > + u32 hi, lo; > > > + > > > + do { > > > + hi = clint_get_cycles_hi(); > > > + lo = clint_get_cycles(); > > > + } while (hi != clint_get_cycles_hi()); > > > + > > > + return ((u64)hi << 32) | lo; > > > +} > > > +#endif /* CONFIG_64BIT */ > > > + > > > +static u64 clint_rdtime(struct clocksource *cs) > > > +{ > > > + return clint_get_cycles64(); > > > +} > > > + > > > +static struct clocksource clint_clocksource = { > > > + .name = "clint_clocksource", > > > + .rating = 300, > > > > nit: Not aligned with other structure members. > > > > > + .mask = CLOCKSOURCE_MASK(64), > > > + .flags = CLOCK_SOURCE_IS_CONTINUOUS, > > > + .read = clint_rdtime, > > > +}; > > > + > > > +static int clint_clock_next_event(unsigned long delta, > > > + struct clock_event_device *ce) > > > +{ > > > + void __iomem *r = clint_timer_cmp + > > > + cpuid_to_hartid_map(smp_processor_id()); > > > + > > > + csr_set(CSR_IE, IE_TIE); > > > + writeq_relaxed(clint_get_cycles64() + delta, r); > > > + return 0; > > > +} > > > + > > > +static DEFINE_PER_CPU(struct clock_event_device, clint_clock_event) = { > > > + .name = "clint_clockevent", > > > + .features = CLOCK_EVT_FEAT_ONESHOT, > > > + .rating = 100, > > > + .set_next_event = clint_clock_next_event, > > > > nit: Not aligned with other structure members. > > Okay, will update. > > > > +}; > > > + > > > +static DEFINE_PER_CPU(bool, clint_clock_event_registered); > > > + > > > +static int clint_timer_starting_cpu(unsigned int cpu) > > > +{ > > > + bool *registered = per_cpu_ptr(&clint_clock_event_registered, cpu); > > > + struct clock_event_device *ce = per_cpu_ptr(&clint_clock_event, cpu); > > > + > > > + if (!(*registered)) { > > > + ce->cpumask = cpumask_of(cpu); > > > + clockevents_config_and_register(ce, clint_timer_freq, 200, > > > + ULONG_MAX); > > > > Is there a specific reason to choose different values from the timer-riscv ? > > The min_delta is set to 100 and max_delta is set to 0x7fffffff in > > timer-riscv driver. > > Not really, I will update. I think it's better to use 100 and ULONG_MAX to > have fewer magic values. > Yeah. Looking at the other timer driver, max_delta is all over the place :). I guess we should just keep the same max/min_delta between riscv timer and clint driver. > > > > > + *registered = true; > > > + } > > > + > > > + enable_percpu_irq(clint_timer_irq, > > > + irq_get_trigger_type(clint_timer_irq)); > > > + return 0; > > > +} > > > + > > > +static int clint_timer_dying_cpu(unsigned int cpu) > > > +{ > > > + disable_percpu_irq(clint_timer_irq); > > > + return 0; > > > +} > > > + > > > +static irqreturn_t clint_timer_interrupt(int irq, void *dev_id) > > > +{ > > > + struct clock_event_device *evdev = this_cpu_ptr(&clint_clock_event); > > > + > > > + csr_clear(CSR_IE, IE_TIE); > > > + evdev->event_handler(evdev); > > > + > > > + return IRQ_HANDLED; > > > +} > > > + > > > +static int __init clint_timer_init_dt(struct device_node *np) > > > +{ > > > + int rc; > > > + u32 i, nr_irqs; > > > + void __iomem *base; > > > + struct of_phandle_args oirq; > > > + > > > + /* > > > + * Ensure that CLINT device interrupts are either RV_IRQ_TIMER or > > > + * RV_IRQ_SOFT. If it's anything else then we ignore the device. > > > + */ > > > + nr_irqs = of_irq_count(np); > > > + for (i = 0; i < nr_irqs; i++) { > > > + if (of_irq_parse_one(np, i, &oirq)) { > > > + pr_err("%pOFP: failed to parse irq %d.\n", np, i); > > > + continue; > > > + } > > > + > > > + if ((oirq.args_count != 1) || > > > + (oirq.args[0] != RV_IRQ_TIMER && > > > + oirq.args[0] != RV_IRQ_SOFT)) { > > > + pr_err("%pOFP: invalid irq %d (hwirq %d)\n", > > > + np, i, oirq.args[0]); > > > + return -ENODEV; > > > + } > > > + > > > + /* Find parent irq domain and map timer irq */ > > > + if (!clint_timer_irq && > > > + oirq.args[0] == RV_IRQ_TIMER && > > > + irq_find_host(oirq.np)) > > > + clint_timer_irq = irq_of_parse_and_map(np, i); > > > + } > > > + > > > + /* If CLINT timer irq not found then fail */ > > > + if (!clint_timer_irq) { > > > + pr_err("%pOFP: timer irq not found\n", np); > > > + return -ENODEV; > > > + } > > > + > > > + base = of_iomap(np, 0); > > > + if (!base) { > > > + pr_err("%pOFP: could not map registers\n", np); > > > + return -ENODEV; > > > + } > > > + > > > + clint_ipi_base = base + CLINT_IPI_OFF; > > > + clint_timer_cmp = base + CLINT_TIMER_CMP_OFF; > > > + clint_timer_val = base + CLINT_TIMER_VAL_OFF; > > > + clint_timer_freq = riscv_timebase; > > > + > > > + pr_info("%pOFP: timer running at %ld Hz\n", np, clint_timer_freq); > > > + > > > + rc = clocksource_register_hz(&clint_clocksource, clint_timer_freq); > > > + if (rc) { > > > + iounmap(base); > > > + pr_err("%pOFP: clocksource register failed [%d]\n", np, rc); > > > + return rc; > > > + } > > > + > > > + sched_clock_register(clint_get_cycles64, 64, clint_timer_freq); > > > + > > > + rc = request_percpu_irq(clint_timer_irq, clint_timer_interrupt, > > > + "clint-timer", &clint_clock_event); > > > + if (rc) { > > > + iounmap(base); > > > + pr_err("registering percpu irq failed [%d]\n", rc); > > > + return rc; > > > + } > > > + > > > + rc = cpuhp_setup_state(CPUHP_AP_CLINT_TIMER_STARTING, > > > + "clockevents/clint/timer:starting", > > > + clint_timer_starting_cpu, > > > + clint_timer_dying_cpu); > > > + if (rc) { > > > + free_irq(clint_timer_irq, &clint_clock_event); > > > + iounmap(base); > > > + pr_err("%pOFP: cpuhp setup state failed [%d]\n", np, rc); > > > + return rc; > > > > All the iounmap & return statements can be moved to a goto at the end > > of the function. > > Okay, will update. > > > > > > + } > > > + > > > + riscv_set_ipi_ops(&clint_ipi_ops); > > > + clint_clear_ipi(); > > > + > > > + return 0; > > > +} > > > + > > > +TIMER_OF_DECLARE(clint_timer, "riscv,clint0", clint_timer_init_dt); > > > +TIMER_OF_DECLARE(clint_timer1, "sifive,clint0", clint_timer_init_dt); > > > diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h > > > index 191772d4a4d7..1451f4625833 100644 > > > --- a/include/linux/cpuhotplug.h > > > +++ b/include/linux/cpuhotplug.h > > > @@ -132,6 +132,7 @@ enum cpuhp_state { > > > CPUHP_AP_MIPS_GIC_TIMER_STARTING, > > > CPUHP_AP_ARC_TIMER_STARTING, > > > CPUHP_AP_RISCV_TIMER_STARTING, > > > + CPUHP_AP_CLINT_TIMER_STARTING, > > > CPUHP_AP_CSKY_TIMER_STARTING, > > > CPUHP_AP_HYPERV_TIMER_STARTING, > > > CPUHP_AP_KVM_STARTING, > > > -- > > > 2.25.1 > > > > > > > > > _______________________________________________ > > > linux-riscv mailing list > > > linux-riscv@lists.infradead.org > > > http://lists.infradead.org/mailman/listinfo/linux-riscv > > > > > > > > -- > > Regards, > > Atish > > Regards, > Anup -- Regards, Atish _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv