From patchwork Mon Apr 20 12:16:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Benjamin Gaignard X-Patchwork-Id: 201760 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CBC99C3815B for ; Mon, 20 Apr 2020 12:17:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A0899206B9 for ; Mon, 20 Apr 2020 12:17:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=st.com header.i=@st.com header.b="XSrJbhlJ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726842AbgDTMRC (ORCPT ); Mon, 20 Apr 2020 08:17:02 -0400 Received: from mx08-00178001.pphosted.com ([91.207.212.93]:26776 "EHLO mx07-00178001.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726987AbgDTMQ5 (ORCPT ); Mon, 20 Apr 2020 08:16:57 -0400 Received: from pps.filterd (m0046660.ppops.net [127.0.0.1]) by mx07-00178001.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 03KCGGYD014492; Mon, 20 Apr 2020 14:16:36 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=st.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=STMicroelectronics; bh=ykAdJuzCEqfvV3T3+9XobxNxIKMC5AF872h8FdNdsig=; b=XSrJbhlJ4c2n8VQJlpjyUwcqk20toGFyL2Hkm9oMyxrJIJiBN0UPEk4yL26KVLHclsQm +eqJucdZa4RBXO07BjibMQIQTxWCvNilojyTRHQFej6vjxPjJVq1/VWmj9wHwDtxLDYq /8hOWbU6RrEDxDZVOkdcsM0vpga8/KqIjl1VQCO9k5+C2mm43DyZ18G+0QLXIvoZFUUu S343IUc/A9+1mkpJ5NGc5GGOnXMssU6FdvvWZIdo7zGXaoC5nQGwucpSCN/hkPxhpQDQ UYn2fwcBdrAxB3ZuGmMvnwp79YT/1dA+onEjNS8djTqeMXzPD3liwOzjXEEu2c2VhOgi 5A== Received: from beta.dmz-eu.st.com (beta.dmz-eu.st.com [164.129.1.35]) by mx07-00178001.pphosted.com with ESMTP id 30fpp8ja4e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 20 Apr 2020 14:16:36 +0200 Received: from euls16034.sgp.st.com (euls16034.sgp.st.com [10.75.44.20]) by beta.dmz-eu.st.com (STMicroelectronics) with ESMTP id 688B8100034; Mon, 20 Apr 2020 14:16:36 +0200 (CEST) Received: from Webmail-eu.st.com (sfhdag3node3.st.com [10.75.127.9]) by euls16034.sgp.st.com (STMicroelectronics) with ESMTP id 88CD820FA76; Mon, 20 Apr 2020 14:16:35 +0200 (CEST) Received: from localhost (10.75.127.51) by SFHDAG3NODE3.st.com (10.75.127.9) with Microsoft SMTP Server (TLS) id 15.0.1347.2; Mon, 20 Apr 2020 14:16:34 +0200 From: Benjamin Gaignard To: , , , , , , , CC: , , , , Benjamin Gaignard , Pascal Paillet Subject: [PATCH v7 5/6] clocksource: Add Low Power STM32 timers driver Date: Mon, 20 Apr 2020 14:16:19 +0200 Message-ID: <20200420121620.2099-6-benjamin.gaignard@st.com> X-Mailer: git-send-email 2.15.0 In-Reply-To: <20200420121620.2099-1-benjamin.gaignard@st.com> References: <20200420121620.2099-1-benjamin.gaignard@st.com> MIME-Version: 1.0 X-Originating-IP: [10.75.127.51] X-ClientProxiedBy: SFHDAG8NODE3.st.com (10.75.127.24) To SFHDAG3NODE3.st.com (10.75.127.9) X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-20_03:2020-04-20,2020-04-20 signatures=0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.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 --- drivers/clocksource/Kconfig | 4 + drivers/clocksource/Makefile | 1 + drivers/clocksource/timer-stm32-lp.c | 221 +++++++++++++++++++++++++++++++++++ 3 files changed, 226 insertions(+) create mode 100644 drivers/clocksource/timer-stm32-lp.c diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig index f2142e6bbea3..22b8d8f1eb40 100644 --- a/drivers/clocksource/Kconfig +++ b/drivers/clocksource/Kconfig @@ -292,6 +292,10 @@ 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 + 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 641ba5383ab5..69f744135cb5 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..0f06b8a337aa --- /dev/null +++ b/drivers/clocksource/timer-stm32-lp.c @@ -0,0 +1,221 @@ +// 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 1000 +#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; + struct device *dev; +}; + +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); + + if (clkevt->event_handler) + 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) { + ret = -EINVAL; + goto out_clk_disable; + } + + irq = platform_get_irq(to_platform_device(pdev->dev.parent), 0); + if (irq <= 0) { + ret = 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); + + priv->dev = &pdev->dev; + + return 0; + +out_clk_disable: + clk_disable_unprepare(ddata->clk); + return ret; +} + +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");