[PATCH v2 07/10] spi: bcm53xx: Implement the spi_mem interface

Boris Brezillon
2018-04-10T22:45:12Z

The spi_mem interface is meant to replace the spi_flash_read() one.
Implement the ->exec_op() method so that we can smoothly get rid of the
old interface.

Note that the current ->flash_read() implementation looks a bit fragile
since it does not take the ->read_opcode passed by the spi-nor layer
into account, which means if might not work with all kind of NORs.

Anyway, I left the logic unchanged and added a few extra checks to make
sure we're receiving something that looks like a NOR read operation.

Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
---
Changes in v2:
- include spi-mem.h
- treat op->addr.val differently since it's now an u64
---
drivers/spi/spi-bcm2835.c | 1 +
drivers/spi/spi-bcm53xx.c | 36 +++++++++++++++++++++++++++++++++++-
2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index f35cc10772f6..41ed371eaf15 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -37,6 +37,7 @@
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/spi/spi.h>
+#include <linux/spi/spi-mem.h>

/* SPI register offsets */
#define BCM2835_SPI_CS 0x00
diff --git a/drivers/spi/spi-bcm53xx.c b/drivers/spi/spi-bcm53xx.c
index d02ceb7a29d1..016059d3160b 100644
--- a/drivers/spi/spi-bcm53xx.c
+++ b/drivers/spi/spi-bcm53xx.c
@@ -257,6 +257,38 @@ static int bcm53xxspi_transfer_one(struct spi_master *master,
return 0;
}

+static int bcm53xxspi_exec_mem_op(struct spi_mem *mem,
+ const struct spi_mem_op *op)
+{
+ struct bcm53xxspi *b53spi = spi_master_get_devdata(mem->spi->master);
+ u32 from;
+
+ /*
+ * FIXME: There's nothing in this driver programming the opcode and
+ * buswidth to be used when a read is done on the mmio window, but it
+ * seems to be used to access a SPI NOR device, so restrict access
+ * access to SPINOR_OP_READ commands.
+ */
+ if (!op->data.nbytes || op->data.dir != SPI_MEM_DATA_IN ||
+ op->addr.nbytes != 3 || op->cmd.opcode != 0x3)
+ return -ENOTSUPP;
+
+ /* Return -ENOTSUPP so that the core can fall back to normal reads. */
+ from = op->addr.val;
+ if (from + op->data.nbytes > BCM53XXSPI_FLASH_WINDOW)
+ return -ENOTSUPP;
+
+ bcm53xxspi_enable_bspi(b53spi);
+ memcpy_fromio(op->data.buf.in, b53spi->mmio_base + from,
+ op->data.nbytes);
+
+ return 0;
+}
+
+static const struct spi_controller_mem_ops bcm53xxspi_mem_ops = {
+ .exec_op = bcm53xxspi_exec_mem_op,
+};
+
static int bcm53xxspi_flash_read(struct spi_device *spi,
struct spi_flash_read_message *msg)
{
@@ -311,8 +343,10 @@ static int bcm53xxspi_bcma_probe(struct bcma_device *core)

master->dev.of_node = dev->of_node;
master->transfer_one = bcm53xxspi_transfer_one;
- if (b53spi->mmio_base)
+ if (b53spi->mmio_base) {
+ master->mem_ops = &bcm53xxspi_mem_ops;
master->spi_flash_read = bcm53xxspi_flash_read;
+ }

bcma_set_drvdata(core, b53spi);

--
2.14.1