Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755607AbcKJSYO (ORCPT ); Thu, 10 Nov 2016 13:24:14 -0500 Received: from foss.arm.com ([217.140.101.70]:56760 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755149AbcKJSYM (ORCPT ); Thu, 10 Nov 2016 13:24:12 -0500 Subject: Re: [PATCH v2 2/3] irqchip: mtk-cirq: Add mediatek mtk-cirq implement To: Youlin Pei References: <1478001122-8664-1-git-send-email-youlin.pei@mediatek.com> <1478001122-8664-3-git-send-email-youlin.pei@mediatek.com> <86twbrj586.fsf@arm.com> <1478234577.7975.29.camel@mtksdaap41> <867f8ilwcl.fsf@arm.com> <1478573833.32099.11.camel@mtksdaap41> Cc: Rob Herring , Matthias Brugger , Thomas Gleixner , Jason Cooper , Mark Rutland , Russell King , linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com, hongkun.cao@mediatek.com, yong.wu@mediatek.com, erin.lo@mediatek.com, chieh-jay.liu@mediatek.com From: Marc Zyngier X-Enigmail-Draft-Status: N1110 Organization: ARM Ltd Message-ID: <1f8f7b9f-7788-18c4-19c5-3c9a7623c188@arm.com> Date: Thu, 10 Nov 2016 18:24:07 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.2.0 MIME-Version: 1.0 In-Reply-To: <1478573833.32099.11.camel@mtksdaap41> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 7165 Lines: 185 On 08/11/16 02:57, Youlin Pei wrote: > On Fri, 2016-11-04 at 22:21 +0000, Marc Zyngier wrote: >> On Fri, Nov 04 2016 at 04:42:57 AM, Youlin Pei wrote: >>> On Tue, 2016-11-01 at 20:49 +0000, Marc Zyngier wrote: >>>> On Tue, Nov 01 2016 at 11:52:01 AM, Youlin Pei wrote: >>>>> In Mediatek SOCs, the CIRQ is a low power interrupt controller >>>>> designed to works outside MCUSYS which comprises with Cortex-Ax >>>>> cores,CCI and GIC. >>>>> >>>>> The CIRQ controller is integrated in between MCUSYS( include >>>>> Cortex-Ax, CCI and GIC ) and interrupt sources as the second >>>>> level interrupt controller. The external interrupts which outside >>>>> MCUSYS will feed through CIRQ then bypass to GIC. CIRQ can monitors >>>>> all edge trigger interupts. When an edge interrupt is triggered, >>>>> CIRQ can record the status and generate a pulse signal to GIC when >>>>> flush command executed. >>>>> >>>>> When system enters sleep mode, MCUSYS will be turned off to improve >>>>> power consumption, also GIC is power down. The edge trigger interrupts >>>>> will be lost in this scenario without CIRQ. >>>>> >>>>> This commit provides the CIRQ irqchip implement. >>>>> >>>>> Signed-off-by: Youlin Pei >>>>> --- >>>>> drivers/irqchip/Makefile | 2 +- >>>>> drivers/irqchip/irq-mtk-cirq.c | 262 ++++++++++++++++++++++++++++++++++++++++ >>>>> 2 files changed, 263 insertions(+), 1 deletion(-) >>>>> create mode 100644 drivers/irqchip/irq-mtk-cirq.c >>>>> >>>>> diff --git a/drivers/irqchip/Makefile b/drivers/irqchip/Makefile >>>>> index e4dbfc8..8f33580 100644 >>>>> --- a/drivers/irqchip/Makefile >>>>> +++ b/drivers/irqchip/Makefile >>>>> @@ -60,7 +60,7 @@ obj-$(CONFIG_BCM7120_L2_IRQ) += irq-bcm7120-l2.o >>>>> obj-$(CONFIG_BRCMSTB_L2_IRQ) += irq-brcmstb-l2.o >>>>> obj-$(CONFIG_KEYSTONE_IRQ) += irq-keystone.o >>>>> obj-$(CONFIG_MIPS_GIC) += irq-mips-gic.o >>>>> -obj-$(CONFIG_ARCH_MEDIATEK) += irq-mtk-sysirq.o >>>>> +obj-$(CONFIG_ARCH_MEDIATEK) += irq-mtk-sysirq.o irq-mtk-cirq.o >>>>> obj-$(CONFIG_ARCH_DIGICOLOR) += irq-digicolor.o >>>>> obj-$(CONFIG_RENESAS_H8300H_INTC) += irq-renesas-h8300h.o >>>>> obj-$(CONFIG_RENESAS_H8S_INTC) += irq-renesas-h8s.o >>>>> diff --git a/drivers/irqchip/irq-mtk-cirq.c b/drivers/irqchip/irq-mtk-cirq.c >>>>> new file mode 100644 >>>>> index 0000000..fc43ef3 >>>>> --- /dev/null >>>>> +++ b/drivers/irqchip/irq-mtk-cirq.c >>>>> @@ -0,0 +1,262 @@ >>>>> +/* >>>>> + * Copyright (c) 2016 MediaTek Inc. >>>>> + * Author: Youlin.Pei >>>>> + * >>>>> + * This program is free software; you can redistribute it and/or modify >>>>> + * it under the terms of the GNU General Public License version 2 as >>>>> + * published by the Free Software Foundation. >>>>> + * >>>>> + * This program is distributed in the hope that it will be useful, >>>>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of >>>>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the >>>>> + * GNU General Public License for more details. >>>>> + */ >>>>> + >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> +#include >>>>> + >>>>> +#define CIRQ_ACK 0x40 >>>>> +#define CIRQ_MASK_SET 0xc0 >>>>> +#define CIRQ_MASK_CLR 0x100 >>>>> +#define CIRQ_SENS_SET 0x180 >>>>> +#define CIRQ_SENS_CLR 0x1c0 >>>>> +#define CIRQ_POL_SET 0x240 >>>>> +#define CIRQ_POL_CLR 0x280 >>>>> +#define CIRQ_CONTROL 0x300 >>>>> + >>>>> +#define CIRQ_EN 0x1 >>>>> +#define CIRQ_EDGE 0x2 >>>>> +#define CIRQ_FLUSH 0x4 >>>>> + >>>>> +#define CIRQ_IRQ_NUM 0x200 >>>>> + >>>>> +struct mtk_cirq_chip_data { >>>>> + void __iomem *base; >>>>> + unsigned int ext_irq_start; >>>>> +}; >>>>> + >>>>> +static struct mtk_cirq_chip_data *cirq_data; >>>> >>>> Are you guaranteed that you'll only ever have a single CIRQ in any >>>> system? >>> >>> In Mediatek's SOC, only hace a single CIRQ. >>> >>>> >>>>> + >>>>> +static void mtk_cirq_write_mask(struct irq_data *data, unsigned int offset) >>>>> +{ >>>>> + struct mtk_cirq_chip_data *chip_data = data->chip_data; >>>>> + unsigned int cirq_num = data->hwirq; >>>>> + u32 mask = 1 << (cirq_num % 32); >>>>> + >>>>> + writel(mask, chip_data->base + offset + (cirq_num / 32) * 4); >>>> >>>> Why can't you use the relaxed accessors? >>> >>> It seems that i use wrong function, i will change the writel to >>> writel_relaxed in next ve >>> >>>> >>>>> +} >>>>> + >>>>> +static void mtk_cirq_mask(struct irq_data *data) >>>>> +{ >>>>> + mtk_cirq_write_mask(data, CIRQ_MASK_SET); >>>>> + irq_chip_mask_parent(data); >>>>> +} >>>>> + >>>>> +static void mtk_cirq_unmask(struct irq_data *data) >>>>> +{ >>>>> + mtk_cirq_write_mask(data, CIRQ_MASK_CLR); >>>>> + irq_chip_unmask_parent(data); >>>>> +} >>>>> + >>>>> +static void mtk_cirq_eoi(struct irq_data *data) >>>>> +{ >>>>> + mtk_cirq_write_mask(data, CIRQ_ACK); >>>> >>>> EOI and ACK have very different semantics. What is this write actually >>>> doing? Also, you're now doing an additional MMIO write on each interrupt >>>> EOI, doubling its cost. Do you really need to do actually signal the HW >>>> that we've EOIed an interrupt? I would have hoped that you'd be able to >>>> put it in "bypass" mode as long as you're not suspending... >>>> >>> >>> When external interrupt happened, CIRQ status register record the status >>> even CIRQ is not enabled. when execute the flush command, CIRQ will >>> resend the signals according to the status. So if don't clear the >>> status, CIRQ will resend the wrong signals. the ACK write operation will >>> clear the status. >> >> But at this time, we haven't suspended yet, and there is nothing to >> replay. Also, you only enable the edge capture when suspending. So what >> are you ACKing here? Can't you simply clear everything right when >> suspending and not do it at all on the fast path? > > I had planned to ACK the status in cirq suspend callback, but > encountered a problem. > following is a piece of code from > http://lxr.free-electrons.com/source/kernel/power/suspend.c#L361 > > arch_suspend_disable_irqs(); ---step1 > BUG_ON(!irqs_disabled()); > > error = syscore_suspend(); > | > ---cirq suspend(); ---step2 > > if ack the status in cirq suspend, the interrupts will be lost which > happened during step1 to step2. > > So would you mind give me some suggestions about this? > Thanks a lot! Right. So maybe there is a way: - On suspend you can iterate over all the cirq interrupts that have been recorded - For each of those, you inspect if it is pending at the GIC level (using the irq_get_irqchip_state helper) - if not pending, you Ack it, because it cannot be delivered anymore - If it is pending, then you know it happened between step 1 and step 2. - You then have the choice of either going into suspend and waking up immediately, or failing the suspend. Thoughts? M. -- Jazz is not dead. It just smells funny...