From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754058AbbKCLUE (ORCPT ); Tue, 3 Nov 2015 06:20:04 -0500 Received: from mail-wi0-f181.google.com ([209.85.212.181]:36961 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753447AbbKCLT7 (ORCPT ); Tue, 3 Nov 2015 06:19:59 -0500 MIME-Version: 1.0 In-Reply-To: <1446545174-14193-2-git-send-email-vigneshr@ti.com> References: <1446545174-14193-1-git-send-email-vigneshr@ti.com> <1446545174-14193-2-git-send-email-vigneshr@ti.com> From: Michal Suchanek Date: Tue, 3 Nov 2015 12:19:18 +0100 Message-ID: Subject: Re: [PATCH v2 1/5] spi: introduce mmap read support for spi flash devices To: Vignesh R Cc: Mark Brown , Tony Lindgren , Russell King , devicetree , Linux Kernel Mailing List , linux-omap@vger.kernel.org, "linux-arm-kernel@lists.infradead.org" , MTD Maling List , linux-spi Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3 November 2015 at 11:06, Vignesh R wrote: > In addition to providing direct access to SPI bus, some spi controller > hardwares (like ti-qspi) provide special memory mapped port > to accesses SPI flash devices in order to increase read performance. > This means the controller can automatically send the SPI signals > required to read data from the SPI flash device. > For this, spi controller needs to know flash specific information like > read command to use, dummy bytes and address width. Once these settings > are populated in hardware registers, any read accesses to flash's memory > map region(SoC specific) through memcpy (or mem-to mem DMA copy) will be > handled by controller hardware. The hardware will automatically generate > SPI signals required to read data from flash and present it to CPU/DMA. > > Introduce spi_mtd_mmap_read() interface to support memory mapped read > over SPI flash devices. SPI master drivers can implement this callback to > support memory mapped read interfaces. m25p80 flash driver and other > flash drivers can call this to request memory mapped read. The interface > should only be used MTD flashes and cannot be used with other SPI devices. > > Signed-off-by: Vignesh R > --- > drivers/spi/spi.c | 35 +++++++++++++++++++++++++++++++++++ > include/linux/spi/spi.h | 23 +++++++++++++++++++++++ > 2 files changed, 58 insertions(+) > > diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c > index a5f53de813d3..5a5c7a7d47f2 100644 > --- a/drivers/spi/spi.c > +++ b/drivers/spi/spi.c > @@ -1059,6 +1059,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread) > } > } > > + mutex_lock(&master->mmap_lock_mutex); > trace_spi_message_start(master->cur_msg); > > if (master->prepare_message) { > @@ -1068,6 +1069,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread) > "failed to prepare message: %d\n", ret); > master->cur_msg->status = ret; > spi_finalize_current_message(master); > + mutex_unlock(&master->mmap_lock_mutex); > return; > } > master->cur_msg_prepared = true; > @@ -1077,6 +1079,7 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread) > if (ret) { > master->cur_msg->status = ret; > spi_finalize_current_message(master); > + mutex_unlock(&master->mmap_lock_mutex); > return; > } > > @@ -1084,8 +1087,10 @@ static void __spi_pump_messages(struct spi_master *master, bool in_kthread) > if (ret) { > dev_err(&master->dev, > "failed to transfer one message from queue\n"); > + mutex_unlock(&master->mmap_lock_mutex); > return; > } > + mutex_unlock(&master->mmap_lock_mutex); > } > > /** > @@ -1732,6 +1737,7 @@ int spi_register_master(struct spi_master *master) > spin_lock_init(&master->queue_lock); > spin_lock_init(&master->bus_lock_spinlock); > mutex_init(&master->bus_lock_mutex); > + mutex_init(&master->mmap_lock_mutex); > master->bus_lock_flag = 0; > init_completion(&master->xfer_completion); > if (!master->max_dma_len) > @@ -2237,6 +2243,35 @@ int spi_async_locked(struct spi_device *spi, struct spi_message *message) > EXPORT_SYMBOL_GPL(spi_async_locked); > > > +int spi_mtd_mmap_read(struct spi_device *spi, loff_t from, size_t len, > + size_t *retlen, u_char *buf, u8 read_opcode, > + u8 addr_width, u8 dummy_bytes) > + > +{ > + struct spi_master *master = spi->master; > + int ret; > + > + if (master->auto_runtime_pm) { > + ret = pm_runtime_get_sync(master->dev.parent); > + if (ret < 0) { > + dev_err(&master->dev, "Failed to power device: %d\n", > + ret); > + goto err; > + } > + } > + mutex_lock(&master->mmap_lock_mutex); > + ret = master->spi_mtd_mmap_read(spi, from, len, retlen, buf, > + read_opcode, addr_width, > + dummy_bytes); > + mutex_unlock(&master->mmap_lock_mutex); > + if (master->auto_runtime_pm) > + pm_runtime_put(master->dev.parent); > + > +err: > + return ret; > +} > +EXPORT_SYMBOL_GPL(spi_mtd_mmap_read); > + > /*-------------------------------------------------------------------------*/ > > /* Utility methods for SPI master protocol drivers, layered on > diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h > index 6b00f18f5e6b..0a6d8ad57357 100644 > --- a/include/linux/spi/spi.h > +++ b/include/linux/spi/spi.h > @@ -297,6 +297,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) > * @flags: other constraints relevant to this driver > * @bus_lock_spinlock: spinlock for SPI bus locking > * @bus_lock_mutex: mutex for SPI bus locking > + * @mmap_lock_mutex: mutex for locking SPI bus when mmap transfer is on. Any reason to not use the bus_lock_mutex here? The bus is busy as much during mmap transfer as it is during any other transfer. Thanks Michal