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[98.183.112.25]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5ec02c2c157sm52730eaf.44.2024.10.23.13.59.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Oct 2024 13:59:20 -0700 (PDT) From: David Lechner Date: Wed, 23 Oct 2024 15:59:09 -0500 Subject: [PATCH RFC v4 02/15] spi: add basic support for SPI offloading Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20241023-dlech-mainline-spi-engine-offload-2-v4-2-f8125b99f5a1@baylibre.com> References: <20241023-dlech-mainline-spi-engine-offload-2-v4-0-f8125b99f5a1@baylibre.com> In-Reply-To: <20241023-dlech-mainline-spi-engine-offload-2-v4-0-f8125b99f5a1@baylibre.com> To: Mark Brown , Jonathan Cameron , Rob Herring , Krzysztof Kozlowski , Conor Dooley , =?utf-8?q?Nuno_S=C3=A1?= , =?utf-8?q?Uwe_Kleine-K=C3=B6?= =?utf-8?q?nig?= Cc: Michael Hennerich , Lars-Peter Clausen , David Jander , Martin Sperl , linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, linux-pwm@vger.kernel.org, David Lechner X-Mailer: b4 0.14.1 Add the basic infrastructure to support SPI offload providers and consumers. SPI offloading is a feature that allows the SPI controller to perform transfers without any CPU intervention. This is useful, e.g. for high-speed data acquisition. SPI controllers with offload support need to implement the get_offload callback and can use the devm_spi_offload_alloc() to allocate offload instances. SPI peripheral drivers will call devm_spi_offload_get() to get a reference to the matching offload instance. This offload instance can then be attached to a SPI message to request offloading that message. It is expected that SPI controllers with offload support will check for the offload instance in the SPI message in the optimize_message() callback and handle it accordingly. CONFIG_SPI_OFFLOAD is intended to be a select-only option. Both consumer and provider drivers should `select SPI_OFFLOAD` in their Kconfig to ensure that the SPI core is built with offload support. Signed-off-by: David Lechner --- v4 changes: * SPI offload functions moved to a separate file instead of spi.c (spi.c is already too long). * struct spi_offload and devm_spi_offload_get() are back, similar to but improved over v1. This avoids having to pass the function ID string to every function call and re-lookup the offload instance. * offload message prepare/unprepare functions are removed. Instead the existing optimize/unoptimize functions should be used. Setting spi_message::offload pointer is used as a flag to differentiate between an offloaded message and a regular message. v3 changes: * Minor changes to doc comments. * Changed to use phandle array for spi-offloads. * Changed id to string to make use of spi-offload-names. v2 changes: * This is a rework of "spi: add core support for controllers with offload capabilities" from v1. * The spi_offload_get() function that Nuno didn't like is gone. Instead, there is now a mapping callback that uses the new generic devicetree binding to request resources automatically when a SPI device is probed. * The spi_offload_enable/disable() functions for dealing with hardware triggers are deferred to a separate patch. * This leaves adding spi_offload_prepare/unprepare() which have been reworked to be a bit more robust. --- drivers/spi/Kconfig | 3 ++ drivers/spi/Makefile | 1 + drivers/spi/spi-offload.c | 104 ++++++++++++++++++++++++++++++++++++++++ include/linux/spi/spi-offload.h | 64 +++++++++++++++++++++++++ include/linux/spi/spi.h | 16 +++++++ 5 files changed, 188 insertions(+) diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 823797217404..d65074b85f62 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -55,6 +55,9 @@ config SPI_MEM This extension is meant to simplify interaction with SPI memories by providing a high-level interface to send memory-like commands. +config SPI_OFFLOAD + bool + comment "SPI Master Controller Drivers" config SPI_AIROHA_SNFI diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index a9b1bc259b68..6a470eb475a2 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -10,6 +10,7 @@ ccflags-$(CONFIG_SPI_DEBUG) := -DDEBUG obj-$(CONFIG_SPI_MASTER) += spi.o obj-$(CONFIG_SPI_MEM) += spi-mem.o obj-$(CONFIG_SPI_MUX) += spi-mux.o +obj-$(CONFIG_SPI_OFFLOAD) += spi-offload.o obj-$(CONFIG_SPI_SPIDEV) += spidev.o obj-$(CONFIG_SPI_LOOPBACK_TEST) += spi-loopback-test.o diff --git a/drivers/spi/spi-offload.c b/drivers/spi/spi-offload.c new file mode 100644 index 000000000000..c344cbf50bdb --- /dev/null +++ b/drivers/spi/spi-offload.c @@ -0,0 +1,104 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2024 Analog Devices Inc. + * Copyright (C) 2024 BayLibre, SAS + */ + +#define DEFAULT_SYMBOL_NAMESPACE SPI_OFFLOAD + +#include +#include +#include +#include +#include +#include +#include +#include + +/** + * devm_spi_offload_alloc() - Allocate offload instances + * @dev: Device for devm purposes + * @num_offloads: Number of offloads to allocate + * @priv_size: Size of private data to allocate for each offload + * + * Offload providers should use this to allocate offload instances. + * + * Return: Pointer to array of offloads or error on failure. + */ +struct spi_offload *devm_spi_offload_alloc(struct device *dev, + size_t num_offloads, + size_t priv_size) +{ + struct spi_offload *offloads; + void *privs; + size_t i; + + offloads = devm_kcalloc(dev, num_offloads, sizeof(*offloads) + priv_size, + GFP_KERNEL); + if (!offloads) + return ERR_PTR(-ENOMEM); + + privs = (void *)(offloads + num_offloads); + + for (i = 0; i < num_offloads; i++) { + struct spi_offload *offload = offloads + i; + void *priv = privs + i * priv_size; + + offload->provider_dev = dev; + offload->priv = priv; + } + + return offloads; +} +EXPORT_SYMBOL_GPL(devm_spi_offload_alloc); + +static void spi_offload_put(void *data) +{ + struct spi_offload *offload = data; + + offload->spi = NULL; + put_device(offload->provider_dev); +} + +/** + * devm_spi_offload_get() - Get an offload instance + * @dev: Device for devm purposes + * @spi: SPI device to use for the transfers + * @config: Offload configuration + * + * Peripheral drivers call this function to get an offload instance that meets + * the requirements specified in @config. If no suitable offload instance is + * available, -ENODEV is returned. + * + * Return: Offload instance or error on failure. + */ +struct spi_offload *devm_spi_offload_get(struct device *dev, + struct spi_device *spi, + const struct spi_offload_config *config) +{ + struct spi_offload *offload; + int ret; + + if (!spi || !config) + return ERR_PTR(-EINVAL); + + if (!spi->controller->get_offload) + return ERR_PTR(-ENODEV); + + offload = spi->controller->get_offload(spi, config); + if (IS_ERR(offload)) + return offload; + + if (offload->spi) + return ERR_PTR(-EBUSY); + + offload->spi = spi; + get_device(offload->provider_dev); + + ret = devm_add_action_or_reset(dev, spi_offload_put, offload); + if (ret) + return ERR_PTR(ret); + + return offload; +} +EXPORT_SYMBOL_GPL(devm_spi_offload_get); diff --git a/include/linux/spi/spi-offload.h b/include/linux/spi/spi-offload.h new file mode 100644 index 000000000000..92a557533b83 --- /dev/null +++ b/include/linux/spi/spi-offload.h @@ -0,0 +1,64 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2024 Analog Devices Inc. + * Copyright (C) 2024 BayLibre, SAS + */ + +/* + * SPI Offloading support. + * + * Some SPI controllers support offloading of SPI transfers. Essentially, this + * is the ability for a SPI controller to perform SPI transfers with minimal + * or even no CPU intervention, e.g. via a specialized SPI controller with a + * hardware trigger or via a conventional SPI controller using a non-Linux MCU + * processor core to offload the work. + */ + +#ifndef __LINUX_SPI_OFFLOAD_H +#define __LINUX_SPI_OFFLOAD_H + +#include + +MODULE_IMPORT_NS(SPI_OFFLOAD); + +struct device; +struct spi_device; + +/* Offload can be triggered by external hardware event. */ +#define SPI_OFFLOAD_CAP_TRIGGER BIT(0) +/* Offload can record and then play back TX data when triggered. */ +#define SPI_OFFLOAD_CAP_TX_STATIC_DATA BIT(1) +/* Offload can get TX data from an external stream source. */ +#define SPI_OFFLOAD_CAP_TX_STREAM_DMA BIT(2) +/* Offload can send RX data to an external stream sink. */ +#define SPI_OFFLOAD_CAP_RX_STREAM_DMA BIT(3) + +/** + * struct spi_offload_config - offload configuration + * + * This is used to request an offload with specific configuration. + */ +struct spi_offload_config { + /** @capability_flags: required capabilities. See %SPI_OFFLOAD_CAP_* */ + u32 capability_flags; +}; + +/** + * struct spi_offload - offload instance + */ +struct spi_offload { + /** @provider_dev: for get/put reference counting */ + struct device *provider_dev; + /** @spi: SPI device that is currently using the offload */ + struct spi_device *spi; + /** @priv: provider driver private data */ + void *priv; +}; + +struct spi_offload *devm_spi_offload_alloc(struct device *dev, + size_t num_offloads, + size_t priv_size); +struct spi_offload *devm_spi_offload_get(struct device *dev, struct spi_device *spi, + const struct spi_offload_config *config); + +#endif /* __LINUX_SPI_OFFLOAD_H */ diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 8497f4747e24..c230d6a209ee 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -31,6 +31,9 @@ struct spi_transfer; struct spi_controller_mem_ops; struct spi_controller_mem_caps; struct spi_message; +struct spi_controller_offload_ops; +struct spi_offload; +struct spi_offload_config; /* * INTERFACES between SPI master-side drivers and SPI slave protocol handlers, @@ -496,6 +499,9 @@ extern struct spi_device *spi_new_ancillary_device(struct spi_device *spi, u8 ch * @mem_ops: optimized/dedicated operations for interactions with SPI memory. * This field is optional and should only be implemented if the * controller has native support for memory like operations. + * @get_offload: callback for controllers with offload support to get matching + * offload instance. Implementations should return -ENODEV if no match is + * found. * @mem_caps: controller capabilities for the handling of memory operations. * @unprepare_message: undo any work done by prepare_message(). * @target_abort: abort the ongoing transfer request on an SPI target controller @@ -740,6 +746,9 @@ struct spi_controller { const struct spi_controller_mem_ops *mem_ops; const struct spi_controller_mem_caps *mem_caps; + struct spi_offload *(*get_offload)(struct spi_device *spi, + const struct spi_offload_config *config); + /* GPIO chip select */ struct gpio_desc **cs_gpiods; bool use_gpio_descriptors; @@ -1108,6 +1117,7 @@ struct spi_transfer { * @state: for use by whichever driver currently owns the message * @opt_state: for use by whichever driver currently owns the message * @resources: for resource management when the SPI message is processed + * @offload: (optional) offload instance used by this message * * A @spi_message is used to execute an atomic sequence of data transfers, * each represented by a struct spi_transfer. The sequence is "atomic" @@ -1168,6 +1178,12 @@ struct spi_message { */ void *opt_state; + /* + * Optional offload instance used by this message. This must be set + * by the peripheral driver before calling spi_optimize_message(). + */ + struct spi_offload *offload; + /* List of spi_res resources when the SPI message is processed */ struct list_head resources; };