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Received: from bhuna.collabora.co.uk ([46.235.227.227]) by bombadil.infradead.org with esmtps (Exim 4.94 #2 (Red Hat Linux)) id 1lfHnx-007Qe0-OC; Sat, 08 May 2021 07:55:19 +0000 Received: from localhost (unknown [IPv6:2a01:e0a:2c:6930:b93f:9fae:b276:a89a]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: bbrezillon) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 950651F44390; Sat, 8 May 2021 08:55:12 +0100 (BST) Date: Sat, 8 May 2021 09:55:06 +0200 From: Boris Brezillon To: Cc: Mark Brown , Miquel Raynal , Vignesh Raghavendra , , Alexandre Torgue , , , , , Subject: Re: [PATCH v2 1/3] spi: spi-mem: add automatic poll status functions Message-ID: <20210508095506.4d0d628a@collabora.com> In-Reply-To: <20210507131756.17028-2-patrice.chotard@foss.st.com> References: <20210507131756.17028-1-patrice.chotard@foss.st.com> <20210507131756.17028-2-patrice.chotard@foss.st.com> Organization: Collabora X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210508_005518_109116_F46229A9 X-CRM114-Status: GOOD ( 39.89 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, 7 May 2021 15:17:54 +0200 wrote: > From: Patrice Chotard > > With STM32 QSPI, it is possible to poll the status register of the device. > This could be done to offload the CPU during an operation (erase or > program a SPI NAND for example). > > spi_mem_poll_status API has been added to handle this feature. > This new function take care of the offload/non-offload cases. > > For the non-offload case, use read_poll_timeout() to poll the status in > order to release CPU during this phase. > > Signed-off-by: Patrice Chotard > Signed-off-by: Christophe Kerello > --- > Changes in v2: > - Indicates the spi_mem_poll_status() timeout unit > - Use 2-byte wide status register > - Add spi_mem_supports_op() call in spi_mem_poll_status() > - Add completion management in spi_mem_poll_status() > - Add offload/non-offload case mangement in spi_mem_poll_status() > - Optimize the non-offload case by using read_poll_timeout() > > drivers/spi/spi-mem.c | 71 +++++++++++++++++++++++++++++++++++++ > include/linux/spi/spi-mem.h | 10 ++++++ > 2 files changed, 81 insertions(+) > > diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c > index 1513553e4080..3f29c604df7d 100644 > --- a/drivers/spi/spi-mem.c > +++ b/drivers/spi/spi-mem.c > @@ -6,6 +6,7 @@ > * Author: Boris Brezillon > */ > #include > +#include > #include > #include > #include > @@ -743,6 +744,75 @@ static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv) > return container_of(drv, struct spi_mem_driver, spidrv.driver); > } > > +/** > + * spi_mem_finalize_op - report completion of spi_mem_op > + * @ctlr: the controller reporting completion > + * > + * Called by SPI drivers using the spi-mem spi_mem_poll_status() > + * implementation to notify it that the current spi_mem_op has > + * finished. > + */ > +void spi_mem_finalize_op(struct spi_controller *ctlr) > +{ > + complete(&ctlr->xfer_completion); > +} > +EXPORT_SYMBOL_GPL(spi_mem_finalize_op); > + > +/** > + * spi_mem_poll_status() - Poll memory device status > + * @mem: SPI memory device > + * @op: the memory operation to execute > + * @mask: status bitmask to ckeck > + * @match: (status & mask) expected value > + * @timeout_ms: timeout in milliseconds > + * > + * This function send a polling status request to the controller driver > + * > + * Return: 0 in case of success, -ETIMEDOUT in case of error, > + * -EOPNOTSUPP if not supported. > + */ > +int spi_mem_poll_status(struct spi_mem *mem, > + const struct spi_mem_op *op, > + u16 mask, u16 match, u16 timeout_ms) > +{ > + struct spi_controller *ctlr = mem->spi->controller; > + unsigned long ms; > + int ret = -EOPNOTSUPP; > + int exec_op_ret; > + u16 *status; > + > + if (!spi_mem_supports_op(mem, op)) > + return ret; You should only test that in the SW-based polling path. The driver ->poll_status() method is expected to check the operation and return -EOPNOTSUPP if HW-based polling doesn't work for this op, no need to check things twice. > + > + if (ctlr->mem_ops && ctlr->mem_ops->poll_status) { > + ret = spi_mem_access_start(mem); > + if (ret) > + return ret; > + > + reinit_completion(&ctlr->xfer_completion); > + > + ret = ctlr->mem_ops->poll_status(mem, op, mask, match, > + timeout_ms); > + > + ms = wait_for_completion_timeout(&ctlr->xfer_completion, > + msecs_to_jiffies(timeout_ms)); Why do you need to wait here? I'd expect the poll_status to take care of this wait. > + > + spi_mem_access_end(mem); > + if (!ms) > + return -ETIMEDOUT; > + } else { > + status = (u16 *)op->data.buf.in; Hm, I don't think it's safe, for 2 reasons: 1/ op->data.buf.in might be a 1byte buffer, but you're doing a 2byte check 2/ data is in big endian in the SPI buffer, which means your check won't work on LE architectures. You really need a dedicated spi_mem_read_status() function that's passed an u16 pointer: int spi_mem_read_status(struct spi_mem *mem, const struct spi_mem_op *op, u16 *status) { const u8 *bytes = (u8 *)op->data.buf.in; int ret; ret = spi_mem_exec_op(mem, op); if (ret) return ret; if (op->data.nbytes > 1) *status = ((u16)bytes[0] << 8) | bytes[1]; else *status = bytes[0]; return 0; } > + ret = read_poll_timeout(spi_mem_exec_op, exec_op_ret, > + ((*status) & mask) == match, 20, > + timeout_ms * 1000, false, mem, op); > + if (exec_op_ret) > + return exec_op_ret; > + } > + I would do something like this instead: int spi_mem_poll_status(struct spi_mem *mem, const struct spi_mem_op *op, u16 mask, u16 match, u16 timeout_ms) { struct spi_controller *ctlr = mem->spi->controller; int ret = -EOPNOTSUPP; if (op->data.nbytes < 1 || op->data.nbytes > 2) return -EINVAL; if (ctlr->mem_ops && ctlr->mem_ops->poll_status) { ret = spi_mem_access_start(mem); if (ret) return ret; ret = ctlr->mem_ops->poll_status(mem, op, mask, match, timeout_ms); spi_mem_access_end(mem); } if (ret == -EOPNOTSUPP) { u16 status; int read_status_ret; if (!spi_mem_supports_op(mem, op)) return -EOPNOTSUPP; ret = read_poll_timeout(spi_mem_read_status, exec_op_ret, (read_status_ret || ((status & mask) == match), 20, timeout_ms * 1000, false, mem, op, &status); if (read_status_ret) return read_status_ret; } return ret; } > + return ret; > +} > +EXPORT_SYMBOL_GPL(spi_mem_poll_status); > + > static int spi_mem_probe(struct spi_device *spi) > { > struct spi_mem_driver *memdrv = to_spi_mem_drv(spi->dev.driver); > @@ -763,6 +833,7 @@ static int spi_mem_probe(struct spi_device *spi) > if (IS_ERR_OR_NULL(mem->name)) > return PTR_ERR_OR_ZERO(mem->name); > > + init_completion(&ctlr->xfer_completion); > spi_set_drvdata(spi, mem); > > return memdrv->probe(mem); > diff --git a/include/linux/spi/spi-mem.h b/include/linux/spi/spi-mem.h > index 2b65c9edc34e..0fbf5d0a3d31 100644 > --- a/include/linux/spi/spi-mem.h > +++ b/include/linux/spi/spi-mem.h > @@ -250,6 +250,7 @@ static inline void *spi_mem_get_drvdata(struct spi_mem *mem) > * the currently mapped area), and the caller of > * spi_mem_dirmap_write() is responsible for calling it again in > * this case. > + * @poll_status: poll memory device status > * > * This interface should be implemented by SPI controllers providing an > * high-level interface to execute SPI memory operation, which is usually the > @@ -274,6 +275,9 @@ struct spi_controller_mem_ops { > u64 offs, size_t len, void *buf); > ssize_t (*dirmap_write)(struct spi_mem_dirmap_desc *desc, > u64 offs, size_t len, const void *buf); > + int (*poll_status)(struct spi_mem *mem, > + const struct spi_mem_op *op, > + u16 mask, u16 match, unsigned long timeout); > }; > > /** > @@ -369,6 +373,12 @@ devm_spi_mem_dirmap_create(struct device *dev, struct spi_mem *mem, > void devm_spi_mem_dirmap_destroy(struct device *dev, > struct spi_mem_dirmap_desc *desc); > > +void spi_mem_finalize_op(struct spi_controller *ctlr); > + > +int spi_mem_poll_status(struct spi_mem *mem, > + const struct spi_mem_op *op, > + u16 mask, u16 match, u16 timeout); > + > int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv, > struct module *owner); > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel