From patchwork Sat Jan 23 01:07:18 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Prakash, Prashanth" X-Patchwork-Id: 8095231 Return-Path: X-Original-To: patchwork-linux-acpi@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 75117BEEED for ; Sat, 23 Jan 2016 01:07:53 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 82C49205CD for ; Sat, 23 Jan 2016 01:07:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 883AF205DC for ; Sat, 23 Jan 2016 01:07:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755369AbcAWBHu (ORCPT ); Fri, 22 Jan 2016 20:07:50 -0500 Received: from smtp.codeaurora.org ([198.145.29.96]:50665 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754948AbcAWBHk (ORCPT ); Fri, 22 Jan 2016 20:07:40 -0500 Received: from smtp.codeaurora.org (localhost [127.0.0.1]) by smtp.codeaurora.org (Postfix) with ESMTP id 9AFAF6049D; Sat, 23 Jan 2016 01:07:39 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 8E54D60498; Sat, 23 Jan 2016 01:07:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_HI, RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=ham version=3.3.1 Received: from pprakash-lnx.qualcomm.com (unknown [129.46.15.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: pprakash@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 616E560490; Sat, 23 Jan 2016 01:07:38 +0000 (UTC) From: Prashanth Prakash To: rjw@rjwysocki.net Cc: ashwin.chaugule@linaro.org, linux-acpi@vger.kernel.org, linaro-acpi@lists.linaro.org, Prashanth Prakash Subject: [PATCH V2 2/4] acpi: cppc: optimized cpc_read and cpc_write Date: Fri, 22 Jan 2016 18:07:18 -0700 Message-Id: <1453511240-20792-3-git-send-email-pprakash@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1453511240-20792-1-git-send-email-pprakash@codeaurora.org> References: <1453511240-20792-1-git-send-email-pprakash@codeaurora.org> X-Virus-Scanned: ClamAV using ClamSMTP Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP cpc_read and cpc_write are used while holding the pcc_lock spin_lock, so they need to be as fast as possible. acpi_os_read/write_memory APIs linearly search through a list for cached mapping which is quite expensive. Since the PCC subspace is already mapped into virtual address space during initialization, we can just add the offset and access the necessary CPPC registers. This patch + similar changes to PCC driver reduce the time per freq. transition from around 200us to about 20us for cppc cpufreq driver Signed-off-by: Prashanth Prakash Acked-by: Ashwin Chaugule --- drivers/acpi/cppc_acpi.c | 80 ++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 64 insertions(+), 16 deletions(-) diff --git a/drivers/acpi/cppc_acpi.c b/drivers/acpi/cppc_acpi.c index 36c3e4d..b85759d 100644 --- a/drivers/acpi/cppc_acpi.c +++ b/drivers/acpi/cppc_acpi.c @@ -67,6 +67,9 @@ static int pcc_subspace_idx = -1; static bool pcc_channel_acquired; static ktime_t deadline; +/* pcc mapped address + header size + offset within PCC subspace */ +#define GET_PCC_VADDR(offs) (pcc_comm_addr + 0x8 + (offs)) + /* * Arbitrary Retries in case the remote processor is slow to respond * to PCC commands. Keeping it high enough to cover emulators where @@ -585,29 +588,74 @@ void acpi_cppc_processor_exit(struct acpi_processor *pr) } EXPORT_SYMBOL_GPL(acpi_cppc_processor_exit); -static u64 get_phys_addr(struct cpc_reg *reg) -{ - /* PCC communication addr space begins at byte offset 0x8. */ - if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) - return (u64)comm_base_addr + 0x8 + reg->address; - else - return reg->address; -} +/* + * Since cpc_read and cpc_write are called while holding pcc_lock, it should be + * as fast as possible. We have already mapped the PCC subspace during init, so + * we can directly write to it. + */ -static void cpc_read(struct cpc_reg *reg, u64 *val) +static int cpc_read(struct cpc_reg *reg, u64 *val) { - u64 addr = get_phys_addr(reg); + int ret_val = 0; + + *val = 0; + if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) { + void *vaddr = GET_PCC_VADDR(reg->address); - acpi_os_read_memory((acpi_physical_address)addr, - val, reg->bit_width); + switch (reg->bit_width) { + case 8: + *val = readb(vaddr); + break; + case 16: + *val = readw(vaddr); + break; + case 32: + *val = readl(vaddr); + break; + case 64: + *val = readq(vaddr); + break; + default: + pr_debug("Error: Cannot read %u bit width from PCC\n", + reg->bit_width); + ret_val = -EFAULT; + } + } else + ret_val = acpi_os_read_memory((acpi_physical_address)reg->address, + val, reg->bit_width); + return ret_val; } -static void cpc_write(struct cpc_reg *reg, u64 val) +static int cpc_write(struct cpc_reg *reg, u64 val) { - u64 addr = get_phys_addr(reg); + int ret_val = 0; + + if (reg->space_id == ACPI_ADR_SPACE_PLATFORM_COMM) { + void *vaddr = GET_PCC_VADDR(reg->address); - acpi_os_write_memory((acpi_physical_address)addr, - val, reg->bit_width); + switch (reg->bit_width) { + case 8: + writeb(val, vaddr); + break; + case 16: + writew(val, vaddr); + break; + case 32: + writel(val, vaddr); + break; + case 64: + writeq(val, vaddr); + break; + default: + pr_debug("Error: Cannot write %u bit width to PCC\n", + reg->bit_width); + ret_val = -EFAULT; + break; + } + } else + ret_val = acpi_os_write_memory((acpi_physical_address)reg->address, + val, reg->bit_width); + return ret_val; } /**