[v8,10/12] pps: generators: Add PPS Generator TIO Driver

Message ID	20240513103813.5666-11-lakshmi.sowjanya.d@intel.com (mailing list archive)
State	New
Headers	show Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.8]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 927C11474AF; Mon, 13 May 2024 10:39:26 +0000 (UTC) From: lakshmi.sowjanya.d@intel.com To: tglx@linutronix.de, jstultz@google.com, giometti@enneenne.com, corbet@lwn.net, linux-kernel@vger.kernel.org Cc: x86@kernel.org, netdev@vger.kernel.org, linux-doc@vger.kernel.org, intel-wired-lan@lists.osuosl.org, andriy.shevchenko@linux.intel.com, eddie.dong@intel.com, christopher.s.hall@intel.com, jesse.brandeburg@intel.com, davem@davemloft.net, alexandre.torgue@foss.st.com, joabreu@synopsys.com, mcoquelin.stm32@gmail.com, perex@perex.cz, linux-sound@vger.kernel.org, anthony.l.nguyen@intel.com, peter.hilber@opensynergy.com, pandith.n@intel.com, subramanian.mohan@intel.com, thejesh.reddy.t.r@intel.com, lakshmi.sowjanya.d@intel.com Subject: [PATCH v8 10/12] pps: generators: Add PPS Generator TIO Driver Date: Mon, 13 May 2024 16:08:11 +0530 Message-Id: <20240513103813.5666-11-lakshmi.sowjanya.d@intel.com> In-Reply-To: <20240513103813.5666-1-lakshmi.sowjanya.d@intel.com> References: <20240513103813.5666-1-lakshmi.sowjanya.d@intel.com> Precedence: bulk MIME-Version: 1.0 Content-Transfer-Encoding: 8bit
Series	Add support for Intel PPS Generator \| expand [v8,00/12] Add support for Intel PPS Generator [v8,01/12] timekeeping: Add base clock properties in clocksource structure [v8,02/12] x86/tsc: Update tsc/art values in the base clock structure [v8,03/12] e1000e: remove convert_art_to_tsc() [v8,04/12] igc: remove convert_art_ns_to_tsc() [v8,05/12] stmmac: intel: remove convert_art_to_tsc() [v8,06/12] ALSA: hda: remove convert_art_to_tsc() [v8,07/12] ice/ptp: remove convert_art_to_tsc() [v8,08/12] x86/tsc: Remove art to tsc conversion functions which are obsolete [v8,09/12] timekeeping: Add function to convert realtime to base clock [v8,10/12] pps: generators: Add PPS Generator TIO Driver [v8,11/12] Documentation: driver-api: pps: Add Intel Timed I/O PPS generator [v8,12/12] ABI: pps: Add ABI documentation for Intel TIO

diff --git a/drivers/pps/generators/Kconfig b/drivers/pps/generators/Kconfig index d615e640fcad..0f090932336f 100644 --- a/drivers/pps/generators/Kconfig +++ b/drivers/pps/generators/Kconfig @@ -12,3 +12,19 @@ config PPS_GENERATOR_PARPORT If you say yes here you get support for a PPS signal generator which utilizes STROBE pin of a parallel port to send PPS signals. It uses parport abstraction layer and hrtimers to precisely control the signal. + +config PPS_GENERATOR_TIO + tristate "TIO PPS signal generator" + depends on X86 && CPU_SUP_INTEL + help + If you say yes here you get support for a PPS TIO signal generator + which generates a pulse at a prescribed time based on the system clock. + It uses time translation and hrtimers to precisely generate a pulse. + This hardware is present on 2019 and newer Intel CPUs. However, this + driver is not useful without adding highly specialized hardware outside + the Linux system to observe these pulses. + + To compile this driver as a module, choose M here: the module + will be called pps_gen_tio. + + If unsure, say N. diff --git a/drivers/pps/generators/Makefile b/drivers/pps/generators/Makefile index 2589fd0f2481..714e847ae193 100644 --- a/drivers/pps/generators/Makefile +++ b/drivers/pps/generators/Makefile @@ -4,5 +4,6 @@ # obj-$(CONFIG_PPS_GENERATOR_PARPORT) += pps_gen_parport.o +obj-$(CONFIG_PPS_GENERATOR_TIO) += pps_gen_tio.o ccflags-$(CONFIG_PPS_DEBUG) := -DDEBUG diff --git a/drivers/pps/generators/pps_gen_tio.c b/drivers/pps/generators/pps_gen_tio.c new file mode 100644 index 000000000000..c6b7f13ffeca --- /dev/null +++ b/drivers/pps/generators/pps_gen_tio.c @@ -0,0 +1,259 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Intel PPS signal Generator Driver + * + * Copyright (C) 2024 Intel Corporation + */ + +#include <linux/bits.h> +#include <linux/bitfield.h> +#include <linux/cleanup.h> +#include <linux/container_of.h> +#include <linux/cpu.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/hrtimer.h> +#include <linux/io-64-nonatomic-hi-lo.h> +#include <linux/kstrtox.h> +#include <linux/mod_devicetable.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/spinlock.h> +#include <linux/sysfs.h> +#include <linux/timekeeping.h> +#include <linux/types.h> + +#include <asm/cpu_device_id.h> + +#define TIOCTL 0x00 +#define TIOCOMPV 0x10 +#define TIOEC 0x30 + +/* Control Register */ +#define TIOCTL_EN BIT(0) +#define TIOCTL_DIR BIT(1) +#define TIOCTL_EP GENMASK(3, 2) +#define TIOCTL_EP_RISING_EDGE FIELD_PREP(TIOCTL_EP, 0) +#define TIOCTL_EP_FALLING_EDGE FIELD_PREP(TIOCTL_EP, 1) +#define TIOCTL_EP_TOGGLE_EDGE FIELD_PREP(TIOCTL_EP, 2) + +#define SAFE_TIME_NS (10 * NSEC_PER_MSEC) /* Safety time to set hrtimer early */ +#define MAGIC_CONST (NSEC_PER_SEC - SAFE_TIME_NS) +#define ART_HW_DELAY_CYCLES 2 + +struct pps_tio { + struct hrtimer timer; + struct device *dev; + spinlock_t lock; + struct attribute_group attrs; + void __iomem *base; + bool enabled; + u32 prev_count; +}; + +static inline u32 pps_tio_read(struct pps_tio *tio, u32 offset) +{ + return readl(tio->base + offset); +} + +static inline void pps_ctl_write(struct pps_tio *tio, u32 value) +{ + writel(value, tio->base + TIOCTL); +} + +/* For COMPV register, It's safer to write higher 32-bit followed by lower 32-bit */ +static inline void pps_compv_write(struct pps_tio *tio, u64 value) +{ + hi_lo_writeq(value, tio->base + TIOCOMPV); +} + +static inline ktime_t first_event(struct pps_tio *tio) +{ + return ktime_set(ktime_get_real_seconds() + 1, MAGIC_CONST); +} + +static u32 pps_tio_disable(struct pps_tio *tio) +{ + u32 ctrl; + + ctrl = pps_tio_read(tio, TIOCTL); + pps_compv_write(tio, 0); + + ctrl &= ~TIOCTL_EN; + pps_ctl_write(tio, ctrl); + tio->prev_count = 0; + + return ctrl; +} + +static void pps_tio_direction_output(struct pps_tio *tio) +{ + u32 ctrl; + + ctrl = pps_tio_disable(tio); + + /* We enable the device, be sure that the 'compare' value is invalid */ + pps_compv_write(tio, 0); + + ctrl &= ~(TIOCTL_DIR | TIOCTL_EP); + ctrl |= TIOCTL_EP_TOGGLE_EDGE; + pps_ctl_write(tio, ctrl); + + ctrl |= TIOCTL_EN; + pps_ctl_write(tio, ctrl); +} + +static bool pps_generate_next_pulse(struct pps_tio *tio, ktime_t expires) +{ + u64 art; + + if (!ktime_real_to_base_clock(expires, CSID_X86_ART, &art)) { + pps_tio_disable(tio); + return false; + } + + pps_compv_write(tio, art - ART_HW_DELAY_CYCLES); + return true; +} + +static enum hrtimer_restart hrtimer_callback(struct hrtimer *timer) +{ + struct pps_tio *tio = container_of(timer, struct pps_tio, timer); + ktime_t expires, now; + u32 event_count; + + guard(spinlock)(&tio->lock); + + /* Check if any event is missed. If an event is missed, TIO will be disabled*/ + event_count = pps_tio_read(tio, TIOEC); + if (tio->prev_count && tio->prev_count == event_count) + goto err; + tio->prev_count = event_count; + expires = hrtimer_get_expires(timer); + now = ktime_get_real(); + + if (now - expires >= SAFE_TIME_NS) + goto err; + + if (!pps_generate_next_pulse(tio, expires + SAFE_TIME_NS)) + return HRTIMER_NORESTART; + + hrtimer_forward(timer, now, NSEC_PER_SEC / 2); + return HRTIMER_RESTART; +err: + dev_err(tio->dev, "Event missed, Disabling Timed I/O"); + pps_tio_disable(tio); + return HRTIMER_NORESTART; +} + +static ssize_t enable_store(struct device *dev, struct device_attribute *attr, const char *buf, + size_t count) +{ + struct pps_tio *tio = dev_get_drvdata(dev); + bool enable; + int err; + + err = kstrtobool(buf, &enable); + if (err) + return err; + + guard(spinlock_irqsave)(&tio->lock); + if (enable && !tio->enabled) { + if (!timekeeping_clocksource_has_base(CSID_X86_ART)) { + dev_err(tio->dev, "PPS cannot be started as clock is not related to ART"); + return -EPERM; + } + pps_tio_direction_output(tio); + hrtimer_start(&tio->timer, first_event(tio), HRTIMER_MODE_ABS); + tio->enabled = true; + } else if (!enable && tio->enabled) { + hrtimer_cancel(&tio->timer); + pps_tio_disable(tio); + tio->enabled = false; + } + return count; +} + +static ssize_t enable_show(struct device *dev, struct device_attribute *devattr, char *buf) +{ + struct pps_tio *tio = dev_get_drvdata(dev); + u32 ctrl; + + ctrl = pps_tio_read(tio, TIOCTL); + ctrl &= TIOCTL_EN; + + return sysfs_emit(buf, "%u\n", ctrl); +} +static DEVICE_ATTR_RW(enable); + +static struct attribute *pps_tio_attrs[] = { + &dev_attr_enable.attr, + NULL +}; +ATTRIBUTE_GROUPS(pps_tio); + +static int pps_tio_probe(struct platform_device *pdev) +{ + struct pps_tio *tio; + + if (!(cpu_feature_enabled(X86_FEATURE_TSC_KNOWN_FREQ) && + cpu_feature_enabled(X86_FEATURE_ART))) { + dev_warn(&pdev->dev, "TSC/ART is not enabled"); + return -ENODEV; + } + + tio = devm_kzalloc(&pdev->dev, sizeof(*tio), GFP_KERNEL); + if (!tio) + return -ENOMEM; + + tio->dev = &pdev->dev; + tio->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(tio->base)) + return PTR_ERR(tio->base); + + pps_tio_disable(tio); + hrtimer_init(&tio->timer, CLOCK_REALTIME, HRTIMER_MODE_ABS); + tio->timer.function = hrtimer_callback; + spin_lock_init(&tio->lock); + tio->enabled = false; + platform_set_drvdata(pdev, tio); + + return 0; +} + +static int pps_tio_remove(struct platform_device *pdev) +{ + struct pps_tio *tio = platform_get_drvdata(pdev); + + hrtimer_cancel(&tio->timer); + pps_tio_disable(tio); + + return 0; +} + +static const struct acpi_device_id intel_pmc_tio_acpi_match[] = { + { "INTC1021" }, + { "INTC1022" }, + { "INTC1023" }, + { "INTC1024" }, + {} +}; +MODULE_DEVICE_TABLE(acpi, intel_pmc_tio_acpi_match); + +static struct platform_driver pps_tio_driver = { + .probe = pps_tio_probe, + .remove = pps_tio_remove, + .driver = { + .name = "intel-pps-generator", + .acpi_match_table = intel_pmc_tio_acpi_match, + .dev_groups = pps_tio_groups, + }, +}; +module_platform_driver(pps_tio_driver); + +MODULE_AUTHOR("Lakshmi Sowjanya D <lakshmi.sowjanya.d@intel.com>"); +MODULE_AUTHOR("Christopher Hall <christopher.s.hall@intel.com>"); +MODULE_AUTHOR("Pandith N <pandith.n@intel.com>"); +MODULE_AUTHOR("Thejesh Reddy T R <thejesh.reddy.t.r@intel.com>"); +MODULE_DESCRIPTION("Intel PMC Time-Aware IO Generator Driver"); +MODULE_LICENSE("GPL");

[v8,10/12] pps: generators: Add PPS Generator TIO Driver

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