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Mon, 17 Feb 2020 14:45:56 +0100 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 92183100038; Mon, 17 Feb 2020 14:45:51 +0100 (CET) Received: from Webmail-eu.st.com (sfhdag3node3.st.com [10.75.127.9]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 8268E2FF5C7; Mon, 17 Feb 2020 14:45:51 +0100 (CET) Received: from localhost (10.75.127.44) by SFHDAG3NODE3.st.com (10.75.127.9) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 17 Feb 2020 14:45:50 +0100 From: Benjamin Gaignard To: , , , , , , , Subject: [PATCH v4 3/3] clocksource: Add Low Power STM32 timers driver Date: Mon, 17 Feb 2020 14:45:46 +0100 Message-ID: <20200217134546.14562-4-benjamin.gaignard@st.com> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20200217134546.14562-1-benjamin.gaignard@st.com> References: <20200217134546.14562-1-benjamin.gaignard@st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.44] X-ClientProxiedBy: SFHDAG7NODE1.st.com (10.75.127.19) To SFHDAG3NODE3.st.com (10.75.127.9) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.572 definitions=2020-02-17_08:2020-02-17, 2020-02-17 signatures=0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200217_054604_208765_52A1672C X-CRM114-Status: GOOD ( 21.90 ) X-Spam-Score: -0.9 (/) X-Spam-Report: SpamAssassin version 3.4.3 on bombadil.infradead.org summary: Content analysis details: (-0.9 points) pts rule name description ---- ---------------------- -------------------------------------------------- -0.7 RCVD_IN_DNSWL_LOW RBL: Sender listed at https://www.dnswl.org/, low trust [91.207.212.93 listed in list.dnswl.org] 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record -0.0 SPF_PASS SPF: sender matches SPF record -0.1 DKIM_VALID_AU Message has a valid DKIM or DK signature from author's domain -0.1 DKIM_VALID_EF Message has a valid DKIM or DK signature from envelope-from domain 0.1 DKIM_SIGNED Message has a DKIM or DK signature, not necessarily valid -0.1 DKIM_VALID Message has at least one valid DKIM or DK signature X-BeenThere: linux-arm-kernel@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, linux-kernel@vger.kernel.org, Pascal Paillet , Benjamin Gaignard , linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org From: Benjamin Gaignard Implement clock event driver using low power STM32 timers. Low power timer counters running even when CPUs are stopped. It could be used as clock event broadcaster to wake up CPUs but not like a clocksource because each it rise an interrupt the counter restart from 0. Low power timers have a 16 bits counter and a prescaler which allow to divide the clock per power of 2 to up 128 to target a 32KHz rate. Signed-off-by: Benjamin Gaignard Signed-off-by: Pascal Paillet --- version 4: - move defines in mfd/stm32-lptimer.h - change compatiblename - reword commit message - make driver Kconfig depends of MFD_STM32_LPTIMER - remove useless include - remove rate and clk fields from the private structure - to add comments about the registers sequence in stm32_clkevent_lp_set_timer - rework probe function and use devm_request_irq() - do not allow module to be removed - make sure that wakeup interrupt is set drivers/clocksource/Kconfig | 7 ++ drivers/clocksource/Makefile | 1 + drivers/clocksource/timer-stm32-lp.c | 213 +++++++++++++++++++++++++++++++++++ 3 files changed, 221 insertions(+) create mode 100644 drivers/clocksource/timer-stm32-lp.c diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index cc909e465823..9fc2b513db6f 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -292,6 +292,13 @@ config CLKSRC_STM32 select CLKSRC_MMIO select TIMER_OF +config CLKSRC_STM32_LP + bool "Low power clocksource for STM32 SoCs" + depends on MFD_STM32_LPTIMER || COMPILE_TEST + help + This option enables support for STM32 low power clockevent available + on STM32 SoCs + config CLKSRC_MPS2 bool "Clocksource for MPS2 SoCs" if COMPILE_TEST depends on GENERIC_SCHED_CLOCK diff --git a/drivers/clocksource/Makefile b/drivers/clocksource/Makefile index 713686faa549..c00fffbd4769 100644 --- a/drivers/clocksource/Makefile +++ b/drivers/clocksource/Makefile @@ -44,6 +44,7 @@ obj-$(CONFIG_BCM_KONA_TIMER) += bcm_kona_timer.o obj-$(CONFIG_CADENCE_TTC_TIMER) += timer-cadence-ttc.o obj-$(CONFIG_CLKSRC_EFM32) += timer-efm32.o obj-$(CONFIG_CLKSRC_STM32) += timer-stm32.o +obj-$(CONFIG_CLKSRC_STM32_LP) += timer-stm32-lp.o obj-$(CONFIG_CLKSRC_EXYNOS_MCT) += exynos_mct.o obj-$(CONFIG_CLKSRC_LPC32XX) += timer-lpc32xx.o obj-$(CONFIG_CLKSRC_MPS2) += mps2-timer.o diff --git a/drivers/clocksource/timer-stm32-lp.c b/drivers/clocksource/timer-stm32-lp.c new file mode 100644 index 000000000000..50eecdb88216 --- /dev/null +++ b/drivers/clocksource/timer-stm32-lp.c @@ -0,0 +1,213 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) STMicroelectronics 2019 - All Rights Reserved + * Authors: Benjamin Gaignard for STMicroelectronics. + * Pascal Paillet for STMicroelectronics. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CFGR_PSC_OFFSET 9 +#define STM32_LP_RATING 400 +#define STM32_TARGET_CLKRATE (32000 * HZ) +#define STM32_LP_MAX_PSC 7 + +struct stm32_lp_private { + struct regmap *reg; + struct clock_event_device clkevt; + unsigned long period; +}; + +static struct stm32_lp_private* +to_priv(struct clock_event_device *clkevt) +{ + return container_of(clkevt, struct stm32_lp_private, clkevt); +} + +static int stm32_clkevent_lp_shutdown(struct clock_event_device *clkevt) +{ + struct stm32_lp_private *priv = to_priv(clkevt); + + regmap_write(priv->reg, STM32_LPTIM_CR, 0); + regmap_write(priv->reg, STM32_LPTIM_IER, 0); + /* clear pending flags */ + regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF); + + return 0; +} + +static int stm32_clkevent_lp_set_timer(unsigned long evt, + struct clock_event_device *clkevt, + int is_periodic) +{ + struct stm32_lp_private *priv = to_priv(clkevt); + + /* disable LPTIMER to be able to write into IER register*/ + regmap_write(priv->reg, STM32_LPTIM_CR, 0); + /* enable ARR interrupt */ + regmap_write(priv->reg, STM32_LPTIM_IER, STM32_LPTIM_ARRMIE); + /* enable LPTIMER to be able to write into ARR register */ + regmap_write(priv->reg, STM32_LPTIM_CR, STM32_LPTIM_ENABLE); + /* set next event counter */ + regmap_write(priv->reg, STM32_LPTIM_ARR, evt); + + /* start counter */ + if (is_periodic) + regmap_write(priv->reg, STM32_LPTIM_CR, + STM32_LPTIM_CNTSTRT | STM32_LPTIM_ENABLE); + else + regmap_write(priv->reg, STM32_LPTIM_CR, + STM32_LPTIM_SNGSTRT | STM32_LPTIM_ENABLE); + + return 0; +} + +static int stm32_clkevent_lp_set_next_event(unsigned long evt, + struct clock_event_device *clkevt) +{ + return stm32_clkevent_lp_set_timer(evt, clkevt, + clockevent_state_periodic(clkevt)); +} + +static int stm32_clkevent_lp_set_periodic(struct clock_event_device *clkevt) +{ + struct stm32_lp_private *priv = to_priv(clkevt); + + return stm32_clkevent_lp_set_timer(priv->period, clkevt, true); +} + +static int stm32_clkevent_lp_set_oneshot(struct clock_event_device *clkevt) +{ + struct stm32_lp_private *priv = to_priv(clkevt); + + return stm32_clkevent_lp_set_timer(priv->period, clkevt, false); +} + +static irqreturn_t stm32_clkevent_lp_irq_handler(int irq, void *dev_id) +{ + struct clock_event_device *clkevt = (struct clock_event_device *)dev_id; + struct stm32_lp_private *priv = to_priv(clkevt); + + regmap_write(priv->reg, STM32_LPTIM_ICR, STM32_LPTIM_ARRMCF); + + clkevt->event_handler(clkevt); + + return IRQ_HANDLED; +} + +static void stm32_clkevent_lp_set_prescaler(struct stm32_lp_private *priv, + unsigned long *rate) +{ + int i; + + for (i = 0; i <= STM32_LP_MAX_PSC; i++) { + if (DIV_ROUND_CLOSEST(*rate, 1 << i) < STM32_TARGET_CLKRATE) + break; + } + + regmap_write(priv->reg, STM32_LPTIM_CFGR, i << CFGR_PSC_OFFSET); + + /* Adjust rate and period given the prescaler value */ + *rate = DIV_ROUND_CLOSEST(*rate, (1 << i)); + priv->period = DIV_ROUND_UP(*rate, HZ); +} + +static void stm32_clkevent_lp_init(struct stm32_lp_private *priv, + struct device_node *np, unsigned long rate) +{ + priv->clkevt.name = np->full_name; + priv->clkevt.cpumask = cpu_possible_mask; + priv->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | + CLOCK_EVT_FEAT_ONESHOT; + priv->clkevt.set_state_shutdown = stm32_clkevent_lp_shutdown; + priv->clkevt.set_state_periodic = stm32_clkevent_lp_set_periodic; + priv->clkevt.set_state_oneshot = stm32_clkevent_lp_set_oneshot; + priv->clkevt.set_next_event = stm32_clkevent_lp_set_next_event; + priv->clkevt.rating = STM32_LP_RATING; + + clockevents_config_and_register(&priv->clkevt, rate, 0x1, + STM32_LPTIM_MAX_ARR); +} + +static int stm32_clkevent_lp_probe(struct platform_device *pdev) +{ + struct stm32_lptimer *ddata = dev_get_drvdata(pdev->dev.parent); + struct stm32_lp_private *priv; + unsigned long rate; + int ret, irq; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->reg = ddata->regmap; + ret = clk_prepare_enable(ddata->clk); + if (ret) + return -EINVAL; + + rate = clk_get_rate(ddata->clk); + if (!rate) + goto out_clk_disable; + + irq = irq_of_parse_and_map(pdev->dev.parent->of_node, 0); + if (!irq) + goto out_clk_disable; + + if (of_property_read_bool(pdev->dev.parent->of_node, "wakeup-source")) { + ret = device_init_wakeup(&pdev->dev, true); + if (ret) + goto out_clk_disable; + + ret = dev_pm_set_wake_irq(&pdev->dev, irq); + if (ret) + goto out_clk_disable; + } + + ret = devm_request_irq(&pdev->dev, irq, stm32_clkevent_lp_irq_handler, + IRQF_TIMER, pdev->name, &priv->clkevt); + if (ret) + goto out_clk_disable; + + stm32_clkevent_lp_set_prescaler(priv, &rate); + + stm32_clkevent_lp_init(priv, pdev->dev.parent->of_node, rate); + + return 0; + +out_clk_disable: + clk_disable_unprepare(ddata->clk); + return -EINVAL; +} + +static int stm32_clkevent_lp_remove(struct platform_device *pdev) +{ + return -EBUSY; /* cannot unregister clockevent */ +} + +static const struct of_device_id stm32_clkevent_lp_of_match[] = { + { .compatible = "st,stm32-lptimer-timer", }, + {}, +}; +MODULE_DEVICE_TABLE(of, stm32_clkevent_lp_of_match); + +static struct platform_driver stm32_clkevent_lp_driver = { + .probe = stm32_clkevent_lp_probe, + .remove = stm32_clkevent_lp_remove, + .driver = { + .name = "stm32-lptimer-timer", + .of_match_table = of_match_ptr(stm32_clkevent_lp_of_match), + }, +}; +module_platform_driver(stm32_clkevent_lp_driver); + +MODULE_ALIAS("platform:stm32-lptimer-timer"); +MODULE_DESCRIPTION("STMicroelectronics STM32 clockevent low power driver"); +MODULE_LICENSE("GPL v2");