[RFC PATCH 02/13] spi-mem: Add dirmap API from Linux
Sean Anderson
seanga2 at gmail.com
Fri Feb 5 05:39:12 CET 2021
This adds the dirmap API originally introduced in Linux commit aa167f3fed0c
("spi: spi-mem: Add a new API to support direct mapping"). This also
includes several follow-up patches and fixes.
Changes from Linux include:
* Added Kconfig option
* Changed struct device to struct udevice
* Changed struct spi_mem to struct spi_slave
Signed-off-by: Sean Anderson <seanga2 at gmail.com>
---
drivers/spi/Kconfig | 10 ++
drivers/spi/spi-mem.c | 270 ++++++++++++++++++++++++++++++++++++++++++
include/spi-mem.h | 99 ++++++++++++++++
3 files changed, 379 insertions(+)
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 1494c91763..9663b20c74 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -40,6 +40,16 @@ config SPI_MEM
This extension is meant to simplify interaction with SPI memories
by providing an high-level interface to send memory-like commands.
+config SPI_DIRMAP
+ bool "SPI direct mapping"
+ depends on SPI_MEM
+ help
+ Enable the SPI direct mapping API. Most modern SPI controllers can
+ directly map a SPI memory (or a portion of the SPI memory) in the CPU
+ address space. Most of the time this brings significant performance
+ improvements as it automates the whole process of sending SPI memory
+ operations every time a new region is accessed.
+
if DM_SPI
config ALTERA_SPI
diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 6772367ef7..597cd63c00 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -21,6 +21,8 @@
#include <spi.h>
#include <spi-mem.h>
#include <dm/device_compat.h>
+#include <dm/devres.h>
+#include <linux/bug.h>
#endif
#ifndef __UBOOT__
@@ -468,6 +470,274 @@ int spi_mem_adjust_op_size(struct spi_slave *slave, struct spi_mem_op *op)
}
EXPORT_SYMBOL_GPL(spi_mem_adjust_op_size);
+#if CONFIG_IS_ENABLED(SPI_DIRMAP)
+static ssize_t spi_mem_no_dirmap_read(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, void *buf)
+{
+ struct spi_mem_op op = desc->info.op_tmpl;
+ int ret;
+
+ op.addr.val = desc->info.offset + offs;
+ op.data.buf.in = buf;
+ op.data.nbytes = len;
+ ret = spi_mem_adjust_op_size(desc->slave, &op);
+ if (ret)
+ return ret;
+
+ ret = spi_mem_exec_op(desc->slave, &op);
+ if (ret)
+ return ret;
+
+ return op.data.nbytes;
+}
+
+static ssize_t spi_mem_no_dirmap_write(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, const void *buf)
+{
+ struct spi_mem_op op = desc->info.op_tmpl;
+ int ret;
+
+ op.addr.val = desc->info.offset + offs;
+ op.data.buf.out = buf;
+ op.data.nbytes = len;
+ ret = spi_mem_adjust_op_size(desc->slave, &op);
+ if (ret)
+ return ret;
+
+ ret = spi_mem_exec_op(desc->slave, &op);
+ if (ret)
+ return ret;
+
+ return op.data.nbytes;
+}
+
+/**
+ * spi_mem_dirmap_create() - Create a direct mapping descriptor
+ * @mem: SPI mem device this direct mapping should be created for
+ * @info: direct mapping information
+ *
+ * This function is creating a direct mapping descriptor which can then be used
+ * to access the memory using spi_mem_dirmap_read() or spi_mem_dirmap_write().
+ * If the SPI controller driver does not support direct mapping, this function
+ * falls back to an implementation using spi_mem_exec_op(), so that the caller
+ * doesn't have to bother implementing a fallback on his own.
+ *
+ * Return: a valid pointer in case of success, and ERR_PTR() otherwise.
+ */
+struct spi_mem_dirmap_desc *
+spi_mem_dirmap_create(struct spi_slave *slave,
+ const struct spi_mem_dirmap_info *info)
+{
+ struct udevice *bus = slave->dev->parent;
+ struct dm_spi_ops *ops = spi_get_ops(bus);
+ struct spi_mem_dirmap_desc *desc;
+ int ret = -ENOTSUPP;
+
+ /* Make sure the number of address cycles is between 1 and 8 bytes. */
+ if (!info->op_tmpl.addr.nbytes || info->op_tmpl.addr.nbytes > 8)
+ return ERR_PTR(-EINVAL);
+
+ /* data.dir should either be SPI_MEM_DATA_IN or SPI_MEM_DATA_OUT. */
+ if (info->op_tmpl.data.dir == SPI_MEM_NO_DATA)
+ return ERR_PTR(-EINVAL);
+
+ desc = kzalloc(sizeof(*desc), GFP_KERNEL);
+ if (!desc)
+ return ERR_PTR(-ENOMEM);
+
+ desc->slave = slave;
+ desc->info = *info;
+ if (ops->mem_ops && ops->mem_ops->dirmap_create)
+ ret = ops->mem_ops->dirmap_create(desc);
+
+ if (ret) {
+ desc->nodirmap = true;
+ if (!spi_mem_supports_op(desc->slave, &desc->info.op_tmpl))
+ ret = -ENOTSUPP;
+ else
+ ret = 0;
+ }
+
+ if (ret) {
+ kfree(desc);
+ return ERR_PTR(ret);
+ }
+
+ return desc;
+}
+EXPORT_SYMBOL_GPL(spi_mem_dirmap_create);
+
+/**
+ * spi_mem_dirmap_destroy() - Destroy a direct mapping descriptor
+ * @desc: the direct mapping descriptor to destroy
+ *
+ * This function destroys a direct mapping descriptor previously created by
+ * spi_mem_dirmap_create().
+ */
+void spi_mem_dirmap_destroy(struct spi_mem_dirmap_desc *desc)
+{
+ struct udevice *bus = desc->slave->dev->parent;
+ struct dm_spi_ops *ops = spi_get_ops(bus);
+
+ if (!desc->nodirmap && ops->mem_ops && ops->mem_ops->dirmap_destroy)
+ ops->mem_ops->dirmap_destroy(desc);
+
+ kfree(desc);
+}
+EXPORT_SYMBOL_GPL(spi_mem_dirmap_destroy);
+
+#ifndef __UBOOT__
+static void devm_spi_mem_dirmap_release(struct udevice *dev, void *res)
+{
+ struct spi_mem_dirmap_desc *desc = *(struct spi_mem_dirmap_desc **)res;
+
+ spi_mem_dirmap_destroy(desc);
+}
+
+/**
+ * devm_spi_mem_dirmap_create() - Create a direct mapping descriptor and attach
+ * it to a device
+ * @dev: device the dirmap desc will be attached to
+ * @mem: SPI mem device this direct mapping should be created for
+ * @info: direct mapping information
+ *
+ * devm_ variant of the spi_mem_dirmap_create() function. See
+ * spi_mem_dirmap_create() for more details.
+ *
+ * Return: a valid pointer in case of success, and ERR_PTR() otherwise.
+ */
+struct spi_mem_dirmap_desc *
+devm_spi_mem_dirmap_create(struct udevice *dev, struct spi_slave *slave,
+ const struct spi_mem_dirmap_info *info)
+{
+ struct spi_mem_dirmap_desc **ptr, *desc;
+
+ ptr = devres_alloc(devm_spi_mem_dirmap_release, sizeof(*ptr),
+ GFP_KERNEL);
+ if (!ptr)
+ return ERR_PTR(-ENOMEM);
+
+ desc = spi_mem_dirmap_create(slave, info);
+ if (IS_ERR(desc)) {
+ devres_free(ptr);
+ } else {
+ *ptr = desc;
+ devres_add(dev, ptr);
+ }
+
+ return desc;
+}
+EXPORT_SYMBOL_GPL(devm_spi_mem_dirmap_create);
+
+static int devm_spi_mem_dirmap_match(struct udevice *dev, void *res, void *data)
+{
+ struct spi_mem_dirmap_desc **ptr = res;
+
+ if (WARN_ON(!ptr || !*ptr))
+ return 0;
+
+ return *ptr == data;
+}
+
+/**
+ * devm_spi_mem_dirmap_destroy() - Destroy a direct mapping descriptor attached
+ * to a device
+ * @dev: device the dirmap desc is attached to
+ * @desc: the direct mapping descriptor to destroy
+ *
+ * devm_ variant of the spi_mem_dirmap_destroy() function. See
+ * spi_mem_dirmap_destroy() for more details.
+ */
+void devm_spi_mem_dirmap_destroy(struct udevice *dev,
+ struct spi_mem_dirmap_desc *desc)
+{
+ devres_release(dev, devm_spi_mem_dirmap_release,
+ devm_spi_mem_dirmap_match, desc);
+}
+EXPORT_SYMBOL_GPL(devm_spi_mem_dirmap_destroy);
+#endif /* __UBOOT__ */
+
+/**
+ * spi_mem_dirmap_read() - Read data through a direct mapping
+ * @desc: direct mapping descriptor
+ * @offs: offset to start reading from. Note that this is not an absolute
+ * offset, but the offset within the direct mapping which already has
+ * its own offset
+ * @len: length in bytes
+ * @buf: destination buffer. This buffer must be DMA-able
+ *
+ * This function reads data from a memory device using a direct mapping
+ * previously instantiated with spi_mem_dirmap_create().
+ *
+ * Return: the amount of data read from the memory device or a negative error
+ * code. Note that the returned size might be smaller than @len, and the caller
+ * is responsible for calling spi_mem_dirmap_read() again when that happens.
+ */
+ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, void *buf)
+{
+ struct udevice *bus = desc->slave->dev->parent;
+ struct dm_spi_ops *ops = spi_get_ops(bus);
+ ssize_t ret;
+
+ if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_IN)
+ return -EINVAL;
+
+ if (!len)
+ return 0;
+
+ if (desc->nodirmap)
+ ret = spi_mem_no_dirmap_read(desc, offs, len, buf);
+ else if (ops->mem_ops && ops->mem_ops->dirmap_read)
+ ret = ops->mem_ops->dirmap_read(desc, offs, len, buf);
+ else
+ ret = -ENOTSUPP;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(spi_mem_dirmap_read);
+
+/**
+ * spi_mem_dirmap_write() - Write data through a direct mapping
+ * @desc: direct mapping descriptor
+ * @offs: offset to start writing from. Note that this is not an absolute
+ * offset, but the offset within the direct mapping which already has
+ * its own offset
+ * @len: length in bytes
+ * @buf: source buffer. This buffer must be DMA-able
+ *
+ * This function writes data to a memory device using a direct mapping
+ * previously instantiated with spi_mem_dirmap_create().
+ *
+ * Return: the amount of data written to the memory device or a negative error
+ * code. Note that the returned size might be smaller than @len, and the caller
+ * is responsible for calling spi_mem_dirmap_write() again when that happens.
+ */
+ssize_t spi_mem_dirmap_write(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, const void *buf)
+{
+ struct udevice *bus = desc->slave->dev->parent;
+ struct dm_spi_ops *ops = spi_get_ops(bus);
+ ssize_t ret;
+
+ if (desc->info.op_tmpl.data.dir != SPI_MEM_DATA_OUT)
+ return -EINVAL;
+
+ if (!len)
+ return 0;
+
+ if (desc->nodirmap)
+ ret = spi_mem_no_dirmap_write(desc, offs, len, buf);
+ else if (ops->mem_ops && ops->mem_ops->dirmap_write)
+ ret = ops->mem_ops->dirmap_write(desc, offs, len, buf);
+ else
+ ret = -ENOTSUPP;
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(spi_mem_dirmap_write);
+#endif /* CONFIG_SPI_DIRMAP */
+
#ifndef __UBOOT__
static inline struct spi_mem_driver *to_spi_mem_drv(struct device_driver *drv)
{
diff --git a/include/spi-mem.h b/include/spi-mem.h
index 1dd556b6cf..d0a247cffc 100644
--- a/include/spi-mem.h
+++ b/include/spi-mem.h
@@ -123,6 +123,49 @@ struct spi_mem_op {
.data = __data, \
}
+/**
+ * struct spi_mem_dirmap_info - Direct mapping information
+ * @op_tmpl: operation template that should be used by the direct mapping when
+ * the memory device is accessed
+ * @offset: absolute offset this direct mapping is pointing to
+ * @length: length in byte of this direct mapping
+ *
+ * These information are used by the controller specific implementation to know
+ * the portion of memory that is directly mapped and the spi_mem_op that should
+ * be used to access the device.
+ * A direct mapping is only valid for one direction (read or write) and this
+ * direction is directly encoded in the ->op_tmpl.data.dir field.
+ */
+struct spi_mem_dirmap_info {
+ struct spi_mem_op op_tmpl;
+ u64 offset;
+ u64 length;
+};
+
+/**
+ * struct spi_mem_dirmap_desc - Direct mapping descriptor
+ * @mem: the SPI memory device this direct mapping is attached to
+ * @info: information passed at direct mapping creation time
+ * @nodirmap: set to 1 if the SPI controller does not implement
+ * ->mem_ops->dirmap_create() or when this function returned an
+ * error. If @nodirmap is true, all spi_mem_dirmap_{read,write}()
+ * calls will use spi_mem_exec_op() to access the memory. This is a
+ * degraded mode that allows spi_mem drivers to use the same code
+ * no matter whether the controller supports direct mapping or not
+ * @priv: field pointing to controller specific data
+ *
+ * Common part of a direct mapping descriptor. This object is created by
+ * spi_mem_dirmap_create() and controller implementation of ->create_dirmap()
+ * can create/attach direct mapping resources to the descriptor in the ->priv
+ * field.
+ */
+struct spi_mem_dirmap_desc {
+ struct spi_slave *slave;
+ struct spi_mem_dirmap_info info;
+ unsigned int nodirmap;
+ void *priv;
+};
+
#ifndef __UBOOT__
/**
* struct spi_mem - describes a SPI memory device
@@ -171,10 +214,32 @@ static inline void *spi_mem_get_drvdata(struct spi_mem *mem)
* limitations)
* @supports_op: check if an operation is supported by the controller
* @exec_op: execute a SPI memory operation
+ * @dirmap_create: create a direct mapping descriptor that can later be used to
+ * access the memory device. This method is optional
+ * @dirmap_destroy: destroy a memory descriptor previous created by
+ * ->dirmap_create()
+ * @dirmap_read: read data from the memory device using the direct mapping
+ * created by ->dirmap_create(). The function can return less
+ * data than requested (for example when the request is crossing
+ * the currently mapped area), and the caller of
+ * spi_mem_dirmap_read() is responsible for calling it again in
+ * this case.
+ * @dirmap_write: write data to the memory device using the direct mapping
+ * created by ->dirmap_create(). The function can return less
+ * data than requested (for example when the request is crossing
+ * the currently mapped area), and the caller of
+ * spi_mem_dirmap_write() is responsible for calling it again in
+ * this case.
*
* This interface should be implemented by SPI controllers providing an
* high-level interface to execute SPI memory operation, which is usually the
* case for QSPI controllers.
+ *
+ * Note on ->dirmap_{read,write}(): drivers should avoid accessing the direct
+ * mapping from the CPU because doing that can stall the CPU waiting for the
+ * SPI mem transaction to finish, and this will make real-time maintainers
+ * unhappy and might make your system less reactive. Instead, drivers should
+ * use DMA to access this direct mapping.
*/
struct spi_controller_mem_ops {
int (*adjust_op_size)(struct spi_slave *slave, struct spi_mem_op *op);
@@ -182,6 +247,12 @@ struct spi_controller_mem_ops {
const struct spi_mem_op *op);
int (*exec_op)(struct spi_slave *slave,
const struct spi_mem_op *op);
+ int (*dirmap_create)(struct spi_mem_dirmap_desc *desc);
+ void (*dirmap_destroy)(struct spi_mem_dirmap_desc *desc);
+ ssize_t (*dirmap_read)(struct spi_mem_dirmap_desc *desc,
+ 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);
};
#ifndef __UBOOT__
@@ -243,6 +314,34 @@ bool spi_mem_supports_op(struct spi_slave *slave, const struct spi_mem_op *op);
int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op);
+#if CONFIG_IS_ENABLED(SPI_DIRMAP)
+struct spi_mem_dirmap_desc *
+spi_mem_dirmap_create(struct spi_slave *mem,
+ const struct spi_mem_dirmap_info *info);
+void spi_mem_dirmap_destroy(struct spi_mem_dirmap_desc *desc);
+ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, void *buf);
+ssize_t spi_mem_dirmap_write(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, const void *buf);
+#else
+static inline void spi_mem_dirmap_destroy(struct spi_mem_dirmap_desc *desc)
+{
+}
+
+static inline ssize_t spi_mem_dirmap_read(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len, void *buf)
+{
+ return -ENOTSUPP;
+}
+
+static inline ssize_t spi_mem_dirmap_write(struct spi_mem_dirmap_desc *desc,
+ u64 offs, size_t len,
+ const void *buf)
+{
+ return -ENOTSUPP;
+}
+#endif /* CONFIG_SPI_DIRMAP */
+
#ifndef __UBOOT__
int spi_mem_driver_register_with_owner(struct spi_mem_driver *drv,
struct module *owner);
--
2.29.2
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