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Wysocki" , Len Brown , Hans de Goede , Mark Gross CC: , , , , , Lucas Tanure , Stefan Binding Subject: [PATCH 1/3] spi: Revert "spi: Remove unused function spi_busnum_to_master()" Date: Thu, 2 Dec 2021 16:24:19 +0000 Message-ID: <20211202162421.7628-1-sbinding@opensource.cirrus.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-Proofpoint-ORIG-GUID: B7iDop18gN-_w8BoDZtY6kLxaA4i6EHT X-Proofpoint-GUID: B7iDop18gN-_w8BoDZtY6kLxaA4i6EHT X-Proofpoint-Spam-Reason: safe Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org From: Lucas Tanure Revert commit bdc7ca008e1f ("spi: Remove unused function spi_busnum_to_master()") This function is needed for the spi version of i2c multi instantiate driver. Signed-off-by: Lucas Tanure Signed-off-by: Stefan Binding --- Documentation/spi/spi-summary.rst | 8 +++++++ drivers/spi/spi.c | 35 +++++++++++++++++++++++++++++++ include/linux/spi/spi.h | 2 ++ 3 files changed, 45 insertions(+) diff --git a/Documentation/spi/spi-summary.rst b/Documentation/spi/spi-summary.rst index aab5d07cb3d7..d4239025461d 100644 --- a/Documentation/spi/spi-summary.rst +++ b/Documentation/spi/spi-summary.rst @@ -336,6 +336,14 @@ certainly includes SPI devices hooked up through the card connectors! Non-static Configurations ^^^^^^^^^^^^^^^^^^^^^^^^^ +Developer boards often play by different rules than product boards, and one +example is the potential need to hotplug SPI devices and/or controllers. + +For those cases you might need to use spi_busnum_to_master() to look +up the spi bus master, and will likely need spi_new_device() to provide the +board info based on the board that was hotplugged. Of course, you'd later +call at least spi_unregister_device() when that board is removed. + When Linux includes support for MMC/SD/SDIO/DataFlash cards through SPI, those configurations will also be dynamic. Fortunately, such devices all support basic device identification probes, so they should hotplug normally. diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 8726309b3eaf..7c81173edb0c 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3145,6 +3145,41 @@ int spi_controller_resume(struct spi_controller *ctlr) } EXPORT_SYMBOL_GPL(spi_controller_resume); +static int __spi_controller_match(struct device *dev, const void *data) +{ + struct spi_controller *ctlr; + const u16 *bus_num = data; + + ctlr = container_of(dev, struct spi_controller, dev); + return ctlr->bus_num == *bus_num; +} + +/** + * spi_busnum_to_master - look up master associated with bus_num + * @bus_num: the master's bus number + * Context: can sleep + * + * This call may be used with devices that are registered after + * arch init time. It returns a refcounted pointer to the relevant + * spi_controller (which the caller must release), or NULL if there is + * no such master registered. + * + * Return: the SPI master structure on success, else NULL. + */ +struct spi_controller *spi_busnum_to_master(u16 bus_num) +{ + struct device *dev; + struct spi_controller *ctlr = NULL; + + dev = class_find_device(&spi_master_class, NULL, &bus_num, + __spi_controller_match); + if (dev) + ctlr = container_of(dev, struct spi_controller, dev); + /* reference got in class_find_device */ + return ctlr; +} +EXPORT_SYMBOL_GPL(spi_busnum_to_master); + /*-------------------------------------------------------------------------*/ /* Core methods for spi_message alterations */ diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index eb7ac8a1e03c..5f2781cb750f 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -759,6 +759,8 @@ extern int devm_spi_register_controller(struct device *dev, struct spi_controller *ctlr); extern void spi_unregister_controller(struct spi_controller *ctlr); +extern struct spi_controller *spi_busnum_to_master(u16 busnum); + /* * SPI resource management while processing a SPI message */ -- 2.25.1