[PATCH] drm/ssd130x: Use new regmap bulk write support to drop custom bus

From: Javier Martinez Canillas
Date: Sat Jun 18 2022 - 13:45:26 EST


Data writes for the ssd130x 4-wire SPI protocol need special handling, due
the Data/Command control (D/C) pin having to be toggled prior to the write.

The regmap API only allowed drivers to provide .reg_{read,write} callbacks
to do per register read/write, but didn't provide a way for drivers to do
the same for bulk read/writes.

For this reason, a custom regmap bus was used by the driver just to define
a bulk write callback that implements the D/C pin toggling. But the regmap
API has been extended to support defining bulk read/write handlers, so the
custom regmap bus is not needed anymore and could just be dropped.

Signed-off-by: Javier Martinez Canillas <javierm@xxxxxxxxxx>
---

This patch depends on the following regmap fixes:

https://lkml.org/lkml/2022/6/16/198


drivers/gpu/drm/solomon/ssd130x-spi.c | 21 +++++----------------
1 file changed, 5 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/solomon/ssd130x-spi.c b/drivers/gpu/drm/solomon/ssd130x-spi.c
index 43722adab1f8..72f066ccd2d9 100644
--- a/drivers/gpu/drm/solomon/ssd130x-spi.c
+++ b/drivers/gpu/drm/solomon/ssd130x-spi.c
@@ -18,11 +18,6 @@ struct ssd130x_spi_transport {
struct gpio_desc *dc;
};

-static const struct regmap_config ssd130x_spi_regmap_config = {
- .reg_bits = 8,
- .val_bits = 8,
-};
-
/*
* The regmap bus .write handler, it is just a wrapper around spi_write()
* but toggling the Data/Command control pin (D/C#). Since for 4-wire SPI
@@ -56,17 +51,12 @@ static int ssd130x_spi_read(void *context, const void *reg, size_t reg_size,
return -EOPNOTSUPP;
}

-/*
- * A custom bus is needed due the special write that toggles a D/C# pin,
- * another option could be to just have a .reg_write() callback but that
- * will prevent to do data writes in bulk.
- *
- * Once the regmap API is extended to support defining a bulk write handler
- * in the struct regmap_config, this can be simplified and the bus dropped.
- */
-static struct regmap_bus regmap_ssd130x_spi_bus = {
+static const struct regmap_config ssd130x_spi_regmap_config = {
+ .reg_bits = 8,
+ .val_bits = 8,
.write = ssd130x_spi_write,
.read = ssd130x_spi_read,
+ .can_multi_write = true,
};

static int ssd130x_spi_probe(struct spi_device *spi)
@@ -90,8 +80,7 @@ static int ssd130x_spi_probe(struct spi_device *spi)
t->spi = spi;
t->dc = dc;

- regmap = devm_regmap_init(dev, &regmap_ssd130x_spi_bus, t,
- &ssd130x_spi_regmap_config);
+ regmap = devm_regmap_init(dev, NULL, t, &ssd130x_spi_regmap_config);
if (IS_ERR(regmap))
return PTR_ERR(regmap);

--
2.36.1