[PATCH v2 1/3] spi: spi-mem: add automatic poll status functions
Boris Brezillon
boris.brezillon at collabora.com
Sat May 8 00:55:06 PDT 2021
On Fri, 7 May 2021 15:17:54 +0200
<patrice.chotard at foss.st.com> wrote:
> From: Patrice Chotard <patrice.chotard at foss.st.com>
>
> 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 <patrice.chotard at foss.st.com>
> Signed-off-by: Christophe Kerello <christophe.kerello at foss.st.com>
> ---
> 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 <boris.brezillon at bootlin.com>
> */
> #include <linux/dmaengine.h>
> +#include <linux/iopoll.h>
> #include <linux/pm_runtime.h>
> #include <linux/spi/spi.h>
> #include <linux/spi/spi-mem.h>
> @@ -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);
>
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