From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754590AbcIITYh (ORCPT ); Fri, 9 Sep 2016 15:24:37 -0400 Received: from mail-ua0-f180.google.com ([209.85.217.180]:34990 "EHLO mail-ua0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754518AbcIITYe (ORCPT ); Fri, 9 Sep 2016 15:24:34 -0400 MIME-Version: 1.0 In-Reply-To: <2529114.aAikiSWl11@wuerfel> References: <1469134557-26869-1-git-send-email-hotran@apm.com> <13081573.BbD3TmEU5Y@wuerfel> <20160907223705.GA31582@roeck-us.net> <2529114.aAikiSWl11@wuerfel> From: Hoan Tran Date: Fri, 9 Sep 2016 12:24:32 -0700 Message-ID: Subject: Re: [PATCH] hwmon: xgene: access mailbox as RAM To: Arnd Bergmann Cc: Guenter Roeck , Jean Delvare , Jonathan Corbet , Rob Herring , Jassi Brar , Ashwin Chaugule , Duc Dang , Loc Ho , linux-hwmon@vger.kernel.org, linux-doc@vger.kernel.org, lkml , linux-arm-kernel@lists.infradead.org, Devicetree List Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Arnd, On Fri, Sep 9, 2016 at 8:38 AM, Arnd Bergmann wrote: > The newly added hwmon driver fails to build in an allmodconfig > kernel: > > 1 ERROR: "memblock_is_memory" [drivers/hwmon/xgene-hwmon.ko] undefined! > > According to comments in the code, the mailbox is a shared memory region, > not a set of MMIO registers, so we should use memremap() for mapping it > instead of ioremap or acpi_os_ioremap, and pointer dereferences instead > of readl/writel. > > The driver already uses plain kernel pointers, so it's a bit unusual > to work with functions that operate on __iomem pointers, and this > fixes that part too. > > I'm using READ_ONCE/WRITE_ONCE here to keep the existing behavior > regarding the ordering of the accesses from the CPU, but note that > there are no barriers (also unchanged from before). > > I'm also keeping the endianess behavior, though I'm unsure whether > the message data was supposed to be in LE32 format in the first > place, it's possible this was meant to be interpreted as a byte > stream instead. > > Signed-off-by: Arnd Bergmann > > diff --git a/drivers/hwmon/xgene-hwmon.c b/drivers/hwmon/xgene-hwmon.c > index bc78a5d10182..e834dfb3acca 100644 > --- a/drivers/hwmon/xgene-hwmon.c > +++ b/drivers/hwmon/xgene-hwmon.c > @@ -34,7 +34,8 @@ > #include > #include > #include > -#include > +#include Alphabetical order. > + > #include > > /* SLIMpro message defines */ > @@ -126,10 +127,10 @@ static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask) > { > u16 ret, val; > > - val = readw_relaxed(addr); > + val = le16_to_cpu(READ_ONCE(*addr)); > ret = val & mask; > val &= ~mask; > - writew_relaxed(val, addr); > + WRITE_ONCE(*addr, cpu_to_le16(val)); > > return ret; > } > @@ -137,7 +138,7 @@ static u16 xgene_word_tst_and_clr(u16 *addr, u16 mask) > static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg) > { > struct acpi_pcct_shared_memory *generic_comm_base = ctx->pcc_comm_addr; > - void *ptr = generic_comm_base + 1; > + u32 *ptr = (void*)(generic_comm_base + 1); Space before "*". > int rc, i; > u16 val; > > @@ -146,21 +147,21 @@ static int xgene_hwmon_pcc_rd(struct xgene_hwmon_dev *ctx, u32 *msg) > ctx->resp_pending = true; > > /* Write signature for subspace */ > - writel_relaxed(PCC_SIGNATURE_MASK | ctx->mbox_idx, > - &generic_comm_base->signature); > + WRITE_ONCE(generic_comm_base->signature, > + cpu_to_le32(PCC_SIGNATURE_MASK | ctx->mbox_idx)); > > /* Write to the shared command region */ > - writew_relaxed(MSG_TYPE(msg[0]) | PCCC_GENERATE_DB_INT, > - &generic_comm_base->command); > + WRITE_ONCE(generic_comm_base->command, > + cpu_to_le16(MSG_TYPE(msg[0]) | PCCC_GENERATE_DB_INT)); > > /* Flip CMD COMPLETE bit */ > - val = readw_relaxed(&generic_comm_base->status); > + val = le16_to_cpu(READ_ONCE(generic_comm_base->status)); > val &= ~PCCS_CMD_COMPLETE; > - writew_relaxed(val, &generic_comm_base->status); > + WRITE_ONCE(generic_comm_base->status, cpu_to_le16(val)); > > /* Copy the message to the PCC comm space */ > for (i = 0; i < sizeof(struct slimpro_resp_msg) / 4; i++) > - writel_relaxed(msg[i], ptr + i * 4); > + WRITE_ONCE(ptr[i], cpu_to_le32(msg[i])); > > /* Ring the doorbell */ > rc = mbox_send_message(ctx->mbox_chan, msg); > @@ -652,9 +653,9 @@ static int xgene_hwmon_probe(struct platform_device *pdev) > */ > ctx->comm_base_addr = cppc_ss->base_address; > if (ctx->comm_base_addr) { > - ctx->pcc_comm_addr = > - acpi_os_ioremap(ctx->comm_base_addr, > - cppc_ss->length); > + ctx->pcc_comm_addr = memremap(ctx->comm_base_addr, > + cppc_ss->length, > + MEMREMAP_WT); It should be MEMREMAP_WB. As mailbox shared memory is on RAM and our co-processor is also in the coherency domain. Thanks Hoan > } else { > dev_err(&pdev->dev, "Failed to get PCC comm region\n"); > rc = -ENODEV; >