Implement SPI offload support for the AXI SPI Engine. Currently, the
hardware only supports triggering offload transfers with a hardware
trigger so attempting to use an offload message in the regular SPI
message queue will fail. Also, only allows streaming rx data to an
external sink, so attempts to use a rx_buf in the offload message will
fail.
Signed-off-by: David Lechner <dlechner@baylibre.com>
---
v4 changes:
* Adapted to changes in other patches in the series.
* Moved trigger enable/disable to same function as offload
enable/disable.
v3 changes:
* Added clk and dma_chan getter callbacks.
* Fixed some bugs.
v2 changes:
This patch has been reworked to accommodate the changes described in all
of the other patches.
---
drivers/spi/Kconfig | 1 +
drivers/spi/spi-axi-spi-engine.c | 273 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 268 insertions(+), 6 deletions(-)
diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
index 50d04fa317b7..af3143ec5245 100644
--- a/drivers/spi/Kconfig
+++ b/drivers/spi/Kconfig
@@ -168,6 +168,7 @@ config SPI_AU1550
config SPI_AXI_SPI_ENGINE
tristate "Analog Devices AXI SPI Engine controller"
depends on HAS_IOMEM
+ select SPI_OFFLOAD
help
This enables support for the Analog Devices AXI SPI Engine SPI controller.
It is part of the SPI Engine framework that is used in some Analog Devices
diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
index 2d24d762b5bd..1710847d81a1 100644
--- a/drivers/spi/spi-axi-spi-engine.c
+++ b/drivers/spi/spi-axi-spi-engine.c
@@ -2,11 +2,14 @@
/*
* SPI-Engine SPI controller driver
* Copyright 2015 Analog Devices Inc.
+ * Copyright 2024 BayLibre, SAS
* Author: Lars-Peter Clausen <lars@metafoo.de>
*/
+#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/completion.h>
+#include <linux/dmaengine.h>
#include <linux/fpga/adi-axi-common.h>
#include <linux/interrupt.h>
#include <linux/io.h>
@@ -14,8 +17,10 @@
#include <linux/module.h>
#include <linux/overflow.h>
#include <linux/platform_device.h>
+#include <linux/spi/spi-offload.h>
#include <linux/spi/spi.h>
+#define SPI_ENGINE_REG_OFFLOAD_MEM_ADDR_WIDTH 0x10
#define SPI_ENGINE_REG_RESET 0x40
#define SPI_ENGINE_REG_INT_ENABLE 0x80
@@ -23,6 +28,7 @@
#define SPI_ENGINE_REG_INT_SOURCE 0x88
#define SPI_ENGINE_REG_SYNC_ID 0xc0
+#define SPI_ENGINE_REG_OFFLOAD_SYNC_ID 0xc4
#define SPI_ENGINE_REG_CMD_FIFO_ROOM 0xd0
#define SPI_ENGINE_REG_SDO_FIFO_ROOM 0xd4
@@ -33,10 +39,24 @@
#define SPI_ENGINE_REG_SDI_DATA_FIFO 0xe8
#define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK 0xec
+#define SPI_ENGINE_MAX_NUM_OFFLOADS 32
+
+#define SPI_ENGINE_REG_OFFLOAD_CTRL(x) (0x100 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_STATUS(x) (0x104 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_RESET(x) (0x108 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_CMD_FIFO(x) (0x110 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+#define SPI_ENGINE_REG_OFFLOAD_SDO_FIFO(x) (0x114 + SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
+
+#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_SDO GENMASK(15, 8)
+#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_CMD GENMASK(7, 0)
+
#define SPI_ENGINE_INT_CMD_ALMOST_EMPTY BIT(0)
#define SPI_ENGINE_INT_SDO_ALMOST_EMPTY BIT(1)
#define SPI_ENGINE_INT_SDI_ALMOST_FULL BIT(2)
#define SPI_ENGINE_INT_SYNC BIT(3)
+#define SPI_ENGINE_INT_OFFLOAD_SYNC BIT(4)
+
+#define SPI_ENGINE_OFFLOAD_CTRL_ENABLE BIT(0)
#define SPI_ENGINE_CONFIG_CPHA BIT(0)
#define SPI_ENGINE_CONFIG_CPOL BIT(1)
@@ -78,6 +98,14 @@
#define SPI_ENGINE_CMD_CS_INV(flags) \
SPI_ENGINE_CMD(SPI_ENGINE_INST_CS_INV, 0, (flags))
+/* default sizes - can be changed when SPI Engine firmware is compiled */
+#define SPI_ENGINE_OFFLOAD_CMD_FIFO_SIZE 16
+#define SPI_ENGINE_OFFLOAD_SDO_FIFO_SIZE 16
+
+#define SPI_ENGINE_OFFLOAD_CAPS (SPI_OFFLOAD_CAP_TRIGGER | \
+ SPI_OFFLOAD_CAP_TX_STATIC_DATA | \
+ SPI_OFFLOAD_CAP_RX_STREAM_DMA)
+
struct spi_engine_program {
unsigned int length;
uint16_t instructions[] __counted_by(length);
@@ -105,6 +133,16 @@ struct spi_engine_message_state {
uint8_t *rx_buf;
};
+enum {
+ SPI_ENGINE_OFFLOAD_FLAG_PREPARED,
+};
+
+struct spi_engine_offload {
+ struct spi_engine *spi_engine;
+ unsigned long flags;
+ unsigned int offload_num;
+};
+
struct spi_engine {
struct clk *clk;
struct clk *ref_clk;
@@ -117,6 +155,11 @@ struct spi_engine {
unsigned int int_enable;
/* shadows hardware CS inversion flag state */
u8 cs_inv;
+
+ unsigned int offload_ctrl_mem_size;
+ unsigned int offload_sdo_mem_size;
+ struct spi_offload *offloads;
+ unsigned int num_offloads;
};
static void spi_engine_program_add_cmd(struct spi_engine_program *p,
@@ -164,7 +207,7 @@ static void spi_engine_gen_xfer(struct spi_engine_program *p, bool dry,
if (xfer->tx_buf)
flags |= SPI_ENGINE_TRANSFER_WRITE;
- if (xfer->rx_buf)
+ if (xfer->rx_buf || (xfer->offload_flags & SPI_OFFLOAD_XFER_RX_STREAM))
flags |= SPI_ENGINE_TRANSFER_READ;
spi_engine_program_add_cmd(p, dry,
@@ -220,16 +263,24 @@ static void spi_engine_gen_cs(struct spi_engine_program *p, bool dry,
*
* NB: This is separate from spi_engine_compile_message() because the latter
* is called twice and would otherwise result in double-evaluation.
+ *
+ * Returns 0 on success, -EINVAL on failure.
*/
-static void spi_engine_precompile_message(struct spi_message *msg)
+static int spi_engine_precompile_message(struct spi_message *msg)
{
unsigned int clk_div, max_hz = msg->spi->controller->max_speed_hz;
struct spi_transfer *xfer;
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ /* If we have an offload transfer, we can't rx to buffer */
+ if (msg->offload && xfer->rx_buf)
+ return -EINVAL;
+
clk_div = DIV_ROUND_UP(max_hz, xfer->speed_hz);
xfer->effective_speed_hz = max_hz / min(clk_div, 256U);
}
+
+ return 0;
}
static void spi_engine_compile_message(struct spi_message *msg, bool dry,
@@ -544,11 +595,94 @@ static irqreturn_t spi_engine_irq(int irq, void *devid)
return IRQ_HANDLED;
}
+static int spi_engine_offload_prepare(struct spi_message *msg)
+{
+ struct spi_controller *host = msg->spi->controller;
+ struct spi_engine *spi_engine = spi_controller_get_devdata(host);
+ struct spi_engine_program *p = msg->opt_state;
+ struct spi_engine_offload *priv = msg->offload->priv;
+ struct spi_transfer *xfer;
+ void __iomem *cmd_addr;
+ void __iomem *sdo_addr;
+ size_t tx_word_count = 0;
+ unsigned int i;
+
+ if (p->length > spi_engine->offload_ctrl_mem_size)
+ return -EINVAL;
+
+ /* count total number of tx words in message */
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ if (!xfer->tx_buf)
+ continue;
+
+ if (xfer->bits_per_word <= 8)
+ tx_word_count += xfer->len;
+ else if (xfer->bits_per_word <= 16)
+ tx_word_count += xfer->len / 2;
+ else
+ tx_word_count += xfer->len / 4;
+ }
+
+ if (tx_word_count > spi_engine->offload_sdo_mem_size)
+ return -EINVAL;
+
+ if (test_and_set_bit_lock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags))
+ return -EBUSY;
+
+ cmd_addr = spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_CMD_FIFO(priv->offload_num);
+ sdo_addr = spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_SDO_FIFO(priv->offload_num);
+
+ list_for_each_entry(xfer, &msg->transfers, transfer_list) {
+ if (!xfer->tx_buf)
+ continue;
+
+ if (xfer->bits_per_word <= 8) {
+ const u8 *buf = xfer->tx_buf;
+
+ for (i = 0; i < xfer->len; i++)
+ writel_relaxed(buf[i], sdo_addr);
+ } else if (xfer->bits_per_word <= 16) {
+ const u16 *buf = xfer->tx_buf;
+
+ for (i = 0; i < xfer->len / 2; i++)
+ writel_relaxed(buf[i], sdo_addr);
+ } else {
+ const u32 *buf = xfer->tx_buf;
+
+ for (i = 0; i < xfer->len / 4; i++)
+ writel_relaxed(buf[i], sdo_addr);
+ }
+ }
+
+ for (i = 0; i < p->length; i++)
+ writel_relaxed(p->instructions[i], cmd_addr);
+
+ return 0;
+}
+
+static void spi_engine_offload_unprepare(struct spi_offload *offload)
+{
+ struct spi_engine_offload *priv = offload->priv;
+ struct spi_engine *spi_engine = priv->spi_engine;
+
+ writel_relaxed(1, spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_RESET(priv->offload_num));
+ writel_relaxed(0, spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_RESET(priv->offload_num));
+
+ clear_bit_unlock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags);
+}
+
static int spi_engine_optimize_message(struct spi_message *msg)
{
struct spi_engine_program p_dry, *p;
+ int ret;
- spi_engine_precompile_message(msg);
+ ret = spi_engine_precompile_message(msg);
+ if (ret)
+ return ret;
p_dry.length = 0;
spi_engine_compile_message(msg, true, &p_dry);
@@ -560,20 +694,54 @@ static int spi_engine_optimize_message(struct spi_message *msg)
spi_engine_compile_message(msg, false, p);
spi_engine_program_add_cmd(p, false, SPI_ENGINE_CMD_SYNC(
- AXI_SPI_ENGINE_CUR_MSG_SYNC_ID));
+ msg->offload ? 0 : AXI_SPI_ENGINE_CUR_MSG_SYNC_ID));
msg->opt_state = p;
+ if (msg->offload) {
+ ret = spi_engine_offload_prepare(msg);
+ if (ret) {
+ msg->opt_state = NULL;
+ kfree(p);
+ return ret;
+ }
+ }
+
return 0;
}
static int spi_engine_unoptimize_message(struct spi_message *msg)
{
+ if (msg->offload)
+ spi_engine_offload_unprepare(msg->offload);
+
kfree(msg->opt_state);
return 0;
}
+static struct spi_offload
+*spi_engine_get_offload(struct spi_device *spi,
+ const struct spi_offload_config *config)
+{
+ struct spi_controller *host = spi->controller;
+ struct spi_engine *spi_engine = spi_controller_get_devdata(host);
+ int i;
+
+ if (config->capability_flags & ~SPI_ENGINE_OFFLOAD_CAPS)
+ return ERR_PTR(-EINVAL);
+
+ for (i = 0; i < spi_engine->num_offloads; i++) {
+ struct spi_offload *offload = &spi_engine->offloads[i];
+ struct spi_engine_offload *priv = offload->priv;
+
+ if (priv->offload_num == spi_get_chipselect(spi, 0))
+ return offload;
+ }
+
+ return ERR_PTR(-ENODEV);
+}
+
static int spi_engine_setup(struct spi_device *device)
{
struct spi_controller *host = device->controller;
@@ -606,6 +774,12 @@ static int spi_engine_transfer_one_message(struct spi_controller *host,
unsigned int int_enable = 0;
unsigned long flags;
+ if (msg->offload) {
+ dev_err(&host->dev, "Single transfer offload not supported\n");
+ msg->status = -EOPNOTSUPP;
+ goto out;
+ }
+
/* reinitialize message state for this transfer */
memset(st, 0, sizeof(*st));
st->cmd_buf = p->instructions;
@@ -641,11 +815,62 @@ static int spi_engine_transfer_one_message(struct spi_controller *host,
msg->status = -ETIMEDOUT;
}
+out:
spi_finalize_current_message(host);
return msg->status;
}
+static int spi_engine_trigger_enable(struct spi_offload *offload)
+{
+ struct spi_controller *host = offload->spi->controller;
+ struct spi_engine_offload *priv = offload->priv;
+ struct spi_engine *spi_engine = priv->spi_engine;
+ unsigned int reg;
+
+ guard(mutex)(&host->io_mutex);
+
+ reg = readl_relaxed(spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+ reg |= SPI_ENGINE_OFFLOAD_CTRL_ENABLE;
+ writel_relaxed(reg, spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+ return 0;
+}
+
+static void spi_engine_trigger_disable(struct spi_offload *offload)
+{
+ struct spi_controller *host = offload->spi->controller;
+ struct spi_engine_offload *priv = offload->priv;
+ struct spi_engine *spi_engine = priv->spi_engine;
+ unsigned int reg;
+
+ guard(mutex)(&host->io_mutex);
+
+ reg = readl_relaxed(spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+ reg &= ~SPI_ENGINE_OFFLOAD_CTRL_ENABLE;
+ writel_relaxed(reg, spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_CTRL(priv->offload_num));
+}
+
+static struct dma_chan
+*spi_engine_rx_stream_request_dma_chan(struct spi_offload *offload)
+{
+ struct spi_engine_offload *priv = offload->priv;
+ char name[16];
+
+ snprintf(name, sizeof(name), "offload%u-rx", priv->offload_num);
+
+ return dma_request_chan(offload->provider_dev, name);
+}
+
+static const struct spi_offload_ops spi_engine_offload_ops = {
+ .trigger_enable = spi_engine_trigger_enable,
+ .trigger_disable = spi_engine_trigger_disable,
+ .rx_stream_request_dma_chan = spi_engine_rx_stream_request_dma_chan,
+};
+
static void spi_engine_release_hw(void *p)
{
struct spi_engine *spi_engine = p;
@@ -660,8 +885,7 @@ static int spi_engine_probe(struct platform_device *pdev)
struct spi_engine *spi_engine;
struct spi_controller *host;
unsigned int version;
- int irq;
- int ret;
+ int irq, ret, i;
irq = platform_get_irq(pdev, 0);
if (irq < 0)
@@ -676,6 +900,29 @@ static int spi_engine_probe(struct platform_device *pdev)
spin_lock_init(&spi_engine->lock);
init_completion(&spi_engine->msg_complete);
+ /*
+ * REVISIT: for now, all SPI Engines only have one offload. In the
+ * future, this should be read from a memory mapped register to
+ * determine the number of offloads enabled at HDL compile time.
+ */
+ spi_engine->num_offloads = 1;
+
+ spi_engine->offloads =
+ devm_spi_offload_alloc(&pdev->dev, spi_engine->num_offloads,
+ sizeof(struct spi_engine_offload));
+ if (IS_ERR(spi_engine->offloads))
+ return PTR_ERR(spi_engine->offloads);
+
+ for (i = 0; i < spi_engine->num_offloads; i++) {
+ struct spi_offload *offload = &spi_engine->offloads[i];
+ struct spi_engine_offload *offload_priv = offload->priv;
+
+ offload->ops = &spi_engine_offload_ops;
+ offload->xfer_flags = SPI_OFFLOAD_XFER_RX_STREAM;
+ offload_priv->spi_engine = spi_engine;
+ offload_priv->offload_num = i;
+ }
+
spi_engine->clk = devm_clk_get_enabled(&pdev->dev, "s_axi_aclk");
if (IS_ERR(spi_engine->clk))
return PTR_ERR(spi_engine->clk);
@@ -697,6 +944,19 @@ static int spi_engine_probe(struct platform_device *pdev)
return -ENODEV;
}
+ if (ADI_AXI_PCORE_VER_MINOR(version) >= 1) {
+ unsigned int sizes = readl(spi_engine->base +
+ SPI_ENGINE_REG_OFFLOAD_MEM_ADDR_WIDTH);
+
+ spi_engine->offload_ctrl_mem_size = 1 <<
+ FIELD_GET(SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_CMD, sizes);
+ spi_engine->offload_sdo_mem_size = 1 <<
+ FIELD_GET(SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_SDO, sizes);
+ } else {
+ spi_engine->offload_ctrl_mem_size = SPI_ENGINE_OFFLOAD_CMD_FIFO_SIZE;
+ spi_engine->offload_sdo_mem_size = SPI_ENGINE_OFFLOAD_SDO_FIFO_SIZE;
+ }
+
writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_RESET);
writel_relaxed(0xff, spi_engine->base + SPI_ENGINE_REG_INT_PENDING);
writel_relaxed(0x00, spi_engine->base + SPI_ENGINE_REG_INT_ENABLE);
@@ -718,6 +978,7 @@ static int spi_engine_probe(struct platform_device *pdev)
host->transfer_one_message = spi_engine_transfer_one_message;
host->optimize_message = spi_engine_optimize_message;
host->unoptimize_message = spi_engine_unoptimize_message;
+ host->get_offload = spi_engine_get_offload;
host->num_chipselect = 8;
/* Some features depend of the IP core version. */
--
2.43.0On Wed, 2024-10-23 at 15:59 -0500, David Lechner wrote:
> Implement SPI offload support for the AXI SPI Engine. Currently, the
> hardware only supports triggering offload transfers with a hardware
> trigger so attempting to use an offload message in the regular SPI
> message queue will fail. Also, only allows streaming rx data to an
> external sink, so attempts to use a rx_buf in the offload message will
> fail.
>
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
>
> v4 changes:
> * Adapted to changes in other patches in the series.
> * Moved trigger enable/disable to same function as offload
> enable/disable.
>
> v3 changes:
> * Added clk and dma_chan getter callbacks.
> * Fixed some bugs.
>
> v2 changes:
>
> This patch has been reworked to accommodate the changes described in all
> of the other patches.
> ---
> drivers/spi/Kconfig | 1 +
> drivers/spi/spi-axi-spi-engine.c | 273 ++++++++++++++++++++++++++++++++++++++-
> 2 files changed, 268 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 50d04fa317b7..af3143ec5245 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -168,6 +168,7 @@ config SPI_AU1550
> config SPI_AXI_SPI_ENGINE
> tristate "Analog Devices AXI SPI Engine controller"
> depends on HAS_IOMEM
> + select SPI_OFFLOAD
> help
> This enables support for the Analog Devices AXI SPI Engine SPI
> controller.
> It is part of the SPI Engine framework that is used in some Analog
> Devices
> diff --git a/drivers/spi/spi-axi-spi-engine.c b/drivers/spi/spi-axi-spi-engine.c
> index 2d24d762b5bd..1710847d81a1 100644
> --- a/drivers/spi/spi-axi-spi-engine.c
> +++ b/drivers/spi/spi-axi-spi-engine.c
> @@ -2,11 +2,14 @@
> /*
> * SPI-Engine SPI controller driver
> * Copyright 2015 Analog Devices Inc.
> + * Copyright 2024 BayLibre, SAS
> * Author: Lars-Peter Clausen <lars@metafoo.de>
> */
>
> +#include <linux/bitops.h>
> #include <linux/clk.h>
> #include <linux/completion.h>
> +#include <linux/dmaengine.h>
> #include <linux/fpga/adi-axi-common.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
> @@ -14,8 +17,10 @@
> #include <linux/module.h>
> #include <linux/overflow.h>
> #include <linux/platform_device.h>
> +#include <linux/spi/spi-offload.h>
> #include <linux/spi/spi.h>
>
...
> +#define SPI_ENGINE_REG_OFFLOAD_MEM_ADDR_WIDTH 0x10
> #define SPI_ENGINE_REG_RESET 0x40
>
> #define SPI_ENGINE_REG_INT_ENABLE 0x80
> @@ -23,6 +28,7 @@
> #define SPI_ENGINE_REG_INT_SOURCE 0x88
>
> #define SPI_ENGINE_REG_SYNC_ID 0xc0
> +#define SPI_ENGINE_REG_OFFLOAD_SYNC_ID 0xc4
>
> #define SPI_ENGINE_REG_CMD_FIFO_ROOM 0xd0
> #define SPI_ENGINE_REG_SDO_FIFO_ROOM 0xd4
> @@ -33,10 +39,24 @@
> #define SPI_ENGINE_REG_SDI_DATA_FIFO 0xe8
> #define SPI_ENGINE_REG_SDI_DATA_FIFO_PEEK 0xec
>
> +#define SPI_ENGINE_MAX_NUM_OFFLOADS 32
> +
> +#define SPI_ENGINE_REG_OFFLOAD_CTRL(x) (0x100 +
> SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
> +#define SPI_ENGINE_REG_OFFLOAD_STATUS(x) (0x104 +
> SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
> +#define SPI_ENGINE_REG_OFFLOAD_RESET(x) (0x108 +
> SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
> +#define SPI_ENGINE_REG_OFFLOAD_CMD_FIFO(x) (0x110 +
> SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
> +#define SPI_ENGINE_REG_OFFLOAD_SDO_FIFO(x) (0x114 +
> SPI_ENGINE_MAX_NUM_OFFLOADS * (x))
> +
> +#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_SDO GENMASK(15, 8)
> +#define SPI_ENGINE_SPI_OFFLOAD_MEM_WIDTH_CMD GENMASK(7, 0)
> +
> #define SPI_ENGINE_INT_CMD_ALMOST_EMPTY BIT(0)
> #define SPI_ENGINE_INT_SDO_ALMOST_EMPTY BIT(1)
> #define SPI_ENGINE_INT_SDI_ALMOST_FULL BIT(2)
> #define SPI_ENGINE_INT_SYNC BIT(3)
> +#define SPI_ENGINE_INT_OFFLOAD_SYNC BIT(4)
> +
> +#define SPI_ENGINE_OFFLOAD_CTRL_ENABLE BIT(0)
>
> #define SPI_ENGINE_CONFIG_CPHA BIT(0)
> #define SPI_ENGINE_CONFIG_CPOL BIT(1)
> @@ -78,6 +98,14 @@
> #define SPI_ENGINE_CMD_CS_INV(flags) \
> SPI_ENGINE_CMD(SPI_ENGINE_INST_CS_INV, 0, (flags))
>
> +/* default sizes - can be changed when SPI Engine firmware is compiled */
> +#define SPI_ENGINE_OFFLOAD_CMD_FIFO_SIZE 16
> +#define SPI_ENGINE_OFFLOAD_SDO_FIFO_SIZE 16
> +
> +#define SPI_ENGINE_OFFLOAD_CAPS (SPI_OFFLOAD_CAP_TRIGGER | \
> + SPI_OFFLOAD_CAP_TX_STATIC_DATA | \
> + SPI_OFFLOAD_CAP_RX_STREAM_DMA)
> +
> struct spi_engine_program {
> unsigned int length;
> uint16_t instructions[] __counted_by(length);
> @@ -105,6 +133,16 @@ struct spi_engine_message_state {
> uint8_t *rx_buf;
> };
>
> +enum {
> + SPI_ENGINE_OFFLOAD_FLAG_PREPARED,
> +};
> +
> +struct spi_engine_offload {
> + struct spi_engine *spi_engine;
> + unsigned long flags;
> + unsigned int offload_num;
> +};
> +
> struct spi_engine {
> struct clk *clk;
> struct clk *ref_clk;
> @@ -117,6 +155,11 @@ struct spi_engine {
> unsigned int int_enable;
> /* shadows hardware CS inversion flag state */
> u8 cs_inv;
> +
> + unsigned int offload_ctrl_mem_size;
> + unsigned int offload_sdo_mem_size;
> + struct spi_offload *offloads;
> + unsigned int num_offloads;
> };
>
> static void spi_engine_program_add_cmd(struct spi_engine_program *p,
> @@ -164,7 +207,7 @@ static void spi_engine_gen_xfer(struct spi_engine_program *p,
> bool dry,
>
> if (xfer->tx_buf)
> flags |= SPI_ENGINE_TRANSFER_WRITE;
> - if (xfer->rx_buf)
> + if (xfer->rx_buf || (xfer->offload_flags &
> SPI_OFFLOAD_XFER_RX_STREAM))
> flags |= SPI_ENGINE_TRANSFER_READ;
>
> spi_engine_program_add_cmd(p, dry,
> @@ -220,16 +263,24 @@ static void spi_engine_gen_cs(struct spi_engine_program *p,
> bool dry,
> *
> * NB: This is separate from spi_engine_compile_message() because the latter
> * is called twice and would otherwise result in double-evaluation.
> + *
> + * Returns 0 on success, -EINVAL on failure.
> */
> -static void spi_engine_precompile_message(struct spi_message *msg)
> +static int spi_engine_precompile_message(struct spi_message *msg)
> {
> unsigned int clk_div, max_hz = msg->spi->controller->max_speed_hz;
> struct spi_transfer *xfer;
>
> list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> + /* If we have an offload transfer, we can't rx to buffer */
> + if (msg->offload && xfer->rx_buf)
> + return -EINVAL;
> +
> clk_div = DIV_ROUND_UP(max_hz, xfer->speed_hz);
> xfer->effective_speed_hz = max_hz / min(clk_div, 256U);
> }
> +
> + return 0;
> }
>
> static void spi_engine_compile_message(struct spi_message *msg, bool dry,
> @@ -544,11 +595,94 @@ static irqreturn_t spi_engine_irq(int irq, void *devid)
> return IRQ_HANDLED;
> }
>
> +static int spi_engine_offload_prepare(struct spi_message *msg)
> +{
> + struct spi_controller *host = msg->spi->controller;
> + struct spi_engine *spi_engine = spi_controller_get_devdata(host);
> + struct spi_engine_program *p = msg->opt_state;
> + struct spi_engine_offload *priv = msg->offload->priv;
> + struct spi_transfer *xfer;
> + void __iomem *cmd_addr;
> + void __iomem *sdo_addr;
> + size_t tx_word_count = 0;
> + unsigned int i;
> +
> + if (p->length > spi_engine->offload_ctrl_mem_size)
> + return -EINVAL;
> +
> + /* count total number of tx words in message */
> + list_for_each_entry(xfer, &msg->transfers, transfer_list) {
> + if (!xfer->tx_buf)
> + continue;
> +
> + if (xfer->bits_per_word <= 8)
> + tx_word_count += xfer->len;
> + else if (xfer->bits_per_word <= 16)
> + tx_word_count += xfer->len / 2;
> + else
> + tx_word_count += xfer->len / 4;
> + }
> +
> + if (tx_word_count > spi_engine->offload_sdo_mem_size)
> + return -EINVAL;
> +
> + if (test_and_set_bit_lock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags))
> + return -EBUSY;
> +
This is odd. Any special reason for using this with aquire - release semantics? Can
optimize() and unoptimize() run concurrently? Because if they can this does not give
us mutual exclusion and we really need to do what we're doing with kind of stuff :)
- Nuno Sá
On 10/25/24 8:09 AM, Nuno Sá wrote:
> On Wed, 2024-10-23 at 15:59 -0500, David Lechner wrote:
>> Implement SPI offload support for the AXI SPI Engine. Currently, the
>> hardware only supports triggering offload transfers with a hardware
>> trigger so attempting to use an offload message in the regular SPI
>> message queue will fail. Also, only allows streaming rx data to an
>> external sink, so attempts to use a rx_buf in the offload message will
>> fail.
>>
>> Signed-off-by: David Lechner <dlechner@baylibre.com>
>> ---
>>
...
>> +static int spi_engine_offload_prepare(struct spi_message *msg)
>> +{
>> + struct spi_controller *host = msg->spi->controller;
>> + struct spi_engine *spi_engine = spi_controller_get_devdata(host);
>> + struct spi_engine_program *p = msg->opt_state;
>> + struct spi_engine_offload *priv = msg->offload->priv;
>> + struct spi_transfer *xfer;
>> + void __iomem *cmd_addr;
>> + void __iomem *sdo_addr;
>> + size_t tx_word_count = 0;
>> + unsigned int i;
>> +
>> + if (p->length > spi_engine->offload_ctrl_mem_size)
>> + return -EINVAL;
>> +
>> + /* count total number of tx words in message */
>> + list_for_each_entry(xfer, &msg->transfers, transfer_list) {
>> + if (!xfer->tx_buf)
>> + continue;
>> +
>> + if (xfer->bits_per_word <= 8)
>> + tx_word_count += xfer->len;
>> + else if (xfer->bits_per_word <= 16)
>> + tx_word_count += xfer->len / 2;
>> + else
>> + tx_word_count += xfer->len / 4;
>> + }
>> +
>> + if (tx_word_count > spi_engine->offload_sdo_mem_size)
>> + return -EINVAL;
>> +
>> + if (test_and_set_bit_lock(SPI_ENGINE_OFFLOAD_FLAG_PREPARED, &priv->flags))
>> + return -EBUSY;
>> +
>
> This is odd. Any special reason for using this with aquire - release semantics? Can
> optimize() and unoptimize() run concurrently? Because if they can this does not give
> us mutual exclusion and we really need to do what we're doing with kind of stuff :)
>
> - Nuno Sá
>
>
This looks like another leftover from an in-between revision that
didn't get fully cleaned up. I will reconsider what is need here.
But to answer the question, strictly speaking, there isn't anything
to prevent two concurrent calls spi_optimize_message() with different
messages but the same offload instance.
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