Re: [PATCH v3 4/4] input: touchscreen: add SPI support for Goodix Berlin Touchscreen IC
From: Neil Armstrong
Date: Mon Jun 26 2023 - 03:02:32 EST
Hi Jeff,
On 25/06/2023 21:38, Jeff LaBundy wrote:
Hi Neil,
On Thu, Jun 22, 2023 at 04:29:02PM +0200, Neil Armstrong wrote:
Add initial support for the new Goodix "Berlin" touchscreen ICs
over the SPI interface.
The driver doesn't use the regmap_spi code since the SPI messages
needs to be prefixed, thus this custom regmap code.
This initial driver is derived from the Goodix goodix_ts_berlin
available at [1] and [2] and only supports the GT9916 IC
present on the Qualcomm SM8550 MTP & QRD touch panel.
The current implementation only supports BerlinD, aka GT9916.
[1] https://github.com/goodix/goodix_ts_berlin
[2] https://git.codelinaro.org/clo/la/platform/vendor/opensource/touch-drivers
Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
---
Just a few comments below, then feel free to add:
Reviewed-by: Jeff LaBundy <jeff@xxxxxxxxxxx>
drivers/input/touchscreen/Kconfig | 13 ++
drivers/input/touchscreen/Makefile | 1 +
drivers/input/touchscreen/goodix_berlin_spi.c | 172 ++++++++++++++++++++++++++
3 files changed, 186 insertions(+)
diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
index 5e21cca6025d..2d86615e5090 100644
--- a/drivers/input/touchscreen/Kconfig
+++ b/drivers/input/touchscreen/Kconfig
@@ -435,6 +435,19 @@ config TOUCHSCREEN_GOODIX_BERLIN_I2C
To compile this driver as a module, choose M here: the
module will be called goodix_berlin_i2c.
+config TOUCHSCREEN_GOODIX_BERLIN_SPI
+ tristate "Goodix Berlin SPI touchscreen"
+ depends on SPI_MASTER
select REGMAP
(keep "depends on SPI_MASTER")
Ack, indeed it looks cleaner to do that
+ select TOUCHSCREEN_GOODIX_BERLIN_CORE
+ help
+ Say Y here if you have a Goodix Berlin IC connected to
+ your system via SPI.
+
+ If unsure, say N.
+
+ To compile this driver as a module, choose M here: the
+ module will be called goodix_berlin_spi.
+
config TOUCHSCREEN_HIDEEP
tristate "HiDeep Touch IC"
depends on I2C
diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
index 921a2da0c2be..29524e8a83db 100644
--- a/drivers/input/touchscreen/Makefile
+++ b/drivers/input/touchscreen/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_TOUCHSCREEN_FUJITSU) += fujitsu_ts.o
obj-$(CONFIG_TOUCHSCREEN_GOODIX) += goodix_ts.o
obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_CORE) += goodix_berlin_core.o
obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_I2C) += goodix_berlin_i2c.o
+obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_SPI) += goodix_berlin_spi.o
obj-$(CONFIG_TOUCHSCREEN_HIDEEP) += hideep.o
obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX) += hynitron_cstxxx.o
obj-$(CONFIG_TOUCHSCREEN_ILI210X) += ili210x.o
diff --git a/drivers/input/touchscreen/goodix_berlin_spi.c b/drivers/input/touchscreen/goodix_berlin_spi.c
new file mode 100644
index 000000000000..3a1bc251b32d
--- /dev/null
+++ b/drivers/input/touchscreen/goodix_berlin_spi.c
@@ -0,0 +1,172 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Goodix Berlin Touchscreen Driver
+ *
+ * Copyright (C) 2020 - 2021 Goodix, Inc.
+ * Copyright (C) 2023 Linaro Ltd.
+ *
+ * Based on goodix_ts_berlin driver.
+ */
+#include <asm/unaligned.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/spi/spi.h>
+
+#include "goodix_berlin.h"
+
+#define SPI_TRANS_PREFIX_LEN 1
+#define REGISTER_WIDTH 4
+#define SPI_READ_DUMMY_LEN 3
+#define SPI_READ_PREFIX_LEN (SPI_TRANS_PREFIX_LEN + REGISTER_WIDTH + SPI_READ_DUMMY_LEN)
+#define SPI_WRITE_PREFIX_LEN (SPI_TRANS_PREFIX_LEN + REGISTER_WIDTH)
+
+#define SPI_WRITE_FLAG 0xF0
+#define SPI_READ_FLAG 0xF1
Please namespace all of these as you have done in the core driver.
Ack
+
+static int goodix_berlin_spi_read(void *context, const void *reg_buf,
+ size_t reg_size, void *val_buf,
+ size_t val_size)
+{
+ struct spi_device *spi = context;
+ struct spi_transfer xfers;
+ struct spi_message spi_msg;
+ const u32 *reg = reg_buf; /* reg is stored as native u32 at start of buffer */
+ u8 *buf;
+ int ret;
int error;
+
+ if (reg_size != REGISTER_WIDTH)
+ return -EINVAL;
+
+ buf = kzalloc(SPI_READ_PREFIX_LEN + val_size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ spi_message_init(&spi_msg);
+ memset(&xfers, 0, sizeof(xfers));
+
+ /* buffer format: 0xF1 + addr(4bytes) + dummy(3bytes) + data */
+ buf[0] = SPI_READ_FLAG;
+ put_unaligned_be32(*reg, buf + SPI_TRANS_PREFIX_LEN);
+ memset(buf + SPI_TRANS_PREFIX_LEN + REGISTER_WIDTH, 0xff,
+ SPI_READ_DUMMY_LEN);
+
+ xfers.tx_buf = buf;
+ xfers.rx_buf = buf;
+ xfers.len = SPI_READ_PREFIX_LEN + val_size;
+ xfers.cs_change = 0;
+ spi_message_add_tail(&xfers, &spi_msg);
+
+ ret = spi_sync(spi, &spi_msg);
error = spi_sync(...);
+ if (ret < 0)
if (error)
+ dev_err(&spi->dev, "transfer error:%d", ret);
+ else
+ memcpy(val_buf, buf + SPI_READ_PREFIX_LEN, val_size);
+
+ kfree(buf);
+ return ret;
+}
+
+static int goodix_berlin_spi_write(void *context, const void *data,
+ size_t count)
+{
+ unsigned int len = count - REGISTER_WIDTH;
+ struct spi_device *spi = context;
+ struct spi_transfer xfers;
+ struct spi_message spi_msg;
+ const u32 *reg = data; /* reg is stored as native u32 at start of buffer */
+ u8 *buf;
+ int ret;
Same comments here regarding 'error' vs. 'ret'.
Seems I forgot to do the rename here, thanks for pointing it!
+
+ buf = kzalloc(SPI_WRITE_PREFIX_LEN + len, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ spi_message_init(&spi_msg);
+ memset(&xfers, 0, sizeof(xfers));
+
+ buf[0] = SPI_WRITE_FLAG;
+ put_unaligned_be32(*reg, buf + SPI_TRANS_PREFIX_LEN);
+ memcpy(buf + SPI_WRITE_PREFIX_LEN, data + REGISTER_WIDTH, len);
+
+ xfers.tx_buf = buf;
+ xfers.len = SPI_WRITE_PREFIX_LEN + len;
+ xfers.cs_change = 0;
+ spi_message_add_tail(&xfers, &spi_msg);
+
+ ret = spi_sync(spi, &spi_msg);
+ if (ret < 0)
+ dev_err(&spi->dev, "transfer error:%d", ret);
+
+ kfree(buf);
+ return ret;
+}
+
+static const struct regmap_config goodix_berlin_spi_regmap_conf = {
+ .reg_bits = 32,
+ .val_bits = 8,
+ .read = goodix_berlin_spi_read,
+ .write = goodix_berlin_spi_write,
+};
+
+/* vendor & product left unassigned here, should probably be updated from fw info */
+static const struct input_id goodix_berlin_spi_input_id = {
+ .bustype = BUS_SPI,
+};
+
+static int goodix_berlin_spi_probe(struct spi_device *spi)
+{
+ struct regmap_config *regmap_config;
+ struct regmap *regmap;
+ size_t max_size;
+ int error = 0;
+
+ regmap_config = devm_kmemdup(&spi->dev, &goodix_berlin_spi_regmap_conf,
+ sizeof(*regmap_config), GFP_KERNEL);
+ if (!regmap_config)
+ return -ENOMEM;
Is there any reason we cannot simply pass goodix_berlin_spi_regmap_conf to
devm_regmap_init() below? Why to duplicate and pass the copy?
For reference, BMP280 in IIO is a similar example of a device with regmap
sitting atop a bespoke SPI protocol; it does not seem to take this extra
step.
The goodix_berlin_spi_regmap_conf copy is modified after with the correct
max raw read/write size, and I'm not a fan of modifying a global structure
that could be use for multiple probes, I can make a copy in a stack variable
if it feels simpler.
+
+ spi->mode = SPI_MODE_0;
+ spi->bits_per_word = 8;
+ error = spi_setup(spi);
+ if (error)
+ return error;
+
+ max_size = spi_max_transfer_size(spi);
+ regmap_config->max_raw_read = max_size - SPI_READ_PREFIX_LEN;
+ regmap_config->max_raw_write = max_size - SPI_WRITE_PREFIX_LEN;
+
+ regmap = devm_regmap_init(&spi->dev, NULL, spi, regmap_config);
+ if (IS_ERR(regmap))
+ return PTR_ERR(regmap);
+
+ return goodix_berlin_probe(&spi->dev, spi->irq,
+ &goodix_berlin_spi_input_id, regmap);
+}
+
+static const struct spi_device_id goodix_berlin_spi_ids[] = {
+ { "gt9916" },
+ { },
+};
+MODULE_DEVICE_TABLE(spi, goodix_berlin_spi_ids);
+
+static const struct of_device_id goodix_berlin_spi_of_match[] = {
+ { .compatible = "goodix,gt9916", },
+ { }
+};
+MODULE_DEVICE_TABLE(of, goodix_berlin_spi_of_match);
+
+static struct spi_driver goodix_berlin_spi_driver = {
+ .driver = {
+ .name = "goodix-berlin-spi",
+ .of_match_table = goodix_berlin_spi_of_match,
+ .pm = pm_sleep_ptr(&goodix_berlin_pm_ops),
+ },
+ .probe = goodix_berlin_spi_probe,
+ .id_table = goodix_berlin_spi_ids,
+};
+module_spi_driver(goodix_berlin_spi_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Goodix Berlin SPI Touchscreen driver");
+MODULE_AUTHOR("Neil Armstrong <neil.armstrong@xxxxxxxxxx>");
--
2.34.1
Kind regards,
Jeff LaBundy
Thanks,
Neil