Re: [PATCH v5 7/7] usb: typec: mux: Add On Semi fsa4480 driver

[Heikki Krogerus]

On Fri, Apr 22, 2022 at 03:23:51PM -0700, Bjorn Andersson wrote:
> The ON Semiconductor FSA4480 is a USB Type-C port multimedia switch with
> support for analog audio headsets. It allows sharing a common USB Type-C
> port to pass USB2.0 signal, analog audio, sideband use wires and analog
> microphone signal.
> 
> Due to lacking upstream audio support for testing, the audio muxing is
> left untouched, but implementation of muxing the SBU lines is provided
> as a pair of Type-C mux and switch devices. This provides the necessary
> support for enabling the DisplayPort altmode on devices with this
> circuit.
> 
> Signed-off-by: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>

Reviewed-by: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx>

> ---
> 
> Changes since v4:
> - Disable locking of the regmap
> - Use dev_fwnode() instead of explicit dereference
> 
>  drivers/usb/typec/mux/Kconfig   |  10 ++
>  drivers/usb/typec/mux/Makefile  |   1 +
>  drivers/usb/typec/mux/fsa4480.c | 218 ++++++++++++++++++++++++++++++++
>  3 files changed, 229 insertions(+)
>  create mode 100644 drivers/usb/typec/mux/fsa4480.c
> 
> diff --git a/drivers/usb/typec/mux/Kconfig b/drivers/usb/typec/mux/Kconfig
> index edead555835e..5eb2c17d72c1 100644
> --- a/drivers/usb/typec/mux/Kconfig
> +++ b/drivers/usb/typec/mux/Kconfig
> @@ -2,6 +2,16 @@
>  
>  menu "USB Type-C Multiplexer/DeMultiplexer Switch support"
>  
> +config TYPEC_MUX_FSA4480
> +	tristate "ON Semi FSA4480 Analog Audio Switch driver"
> +	depends on I2C
> +	select REGMAP_I2C
> +	help
> +	  Driver for the ON Semiconductor FSA4480 Analog Audio Switch, which
> +	  provides support for muxing analog audio and sideband signals on a
> +	  common USB Type-C connector.
> +	  If compiled as a module, the module will be named fsa4480.
> +
>  config TYPEC_MUX_PI3USB30532
>  	tristate "Pericom PI3USB30532 Type-C cross switch driver"
>  	depends on I2C
> diff --git a/drivers/usb/typec/mux/Makefile b/drivers/usb/typec/mux/Makefile
> index 280a6f553115..e52a56c16bfb 100644
> --- a/drivers/usb/typec/mux/Makefile
> +++ b/drivers/usb/typec/mux/Makefile
> @@ -1,4 +1,5 @@
>  # SPDX-License-Identifier: GPL-2.0
>  
> +obj-$(CONFIG_TYPEC_MUX_FSA4480)		+= fsa4480.o
>  obj-$(CONFIG_TYPEC_MUX_PI3USB30532)	+= pi3usb30532.o
>  obj-$(CONFIG_TYPEC_MUX_INTEL_PMC)	+= intel_pmc_mux.o
> diff --git a/drivers/usb/typec/mux/fsa4480.c b/drivers/usb/typec/mux/fsa4480.c
> new file mode 100644
> index 000000000000..6184f5367190
> --- /dev/null
> +++ b/drivers/usb/typec/mux/fsa4480.c
> @@ -0,0 +1,218 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2021-2022 Linaro Ltd.
> + * Copyright (C) 2018-2020 The Linux Foundation
> + */
> +
> +#include <linux/bits.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/regmap.h>
> +#include <linux/usb/typec_dp.h>
> +#include <linux/usb/typec_mux.h>
> +
> +#define FSA4480_SWITCH_ENABLE	0x04
> +#define FSA4480_SWITCH_SELECT	0x05
> +#define FSA4480_SWITCH_STATUS1	0x07
> +#define FSA4480_SLOW_L		0x08
> +#define FSA4480_SLOW_R		0x09
> +#define FSA4480_SLOW_MIC	0x0a
> +#define FSA4480_SLOW_SENSE	0x0b
> +#define FSA4480_SLOW_GND	0x0c
> +#define FSA4480_DELAY_L_R	0x0d
> +#define FSA4480_DELAY_L_MIC	0x0e
> +#define FSA4480_DELAY_L_SENSE	0x0f
> +#define FSA4480_DELAY_L_AGND	0x10
> +#define FSA4480_RESET		0x1e
> +#define FSA4480_MAX_REGISTER	0x1f
> +
> +#define FSA4480_ENABLE_DEVICE	BIT(7)
> +#define FSA4480_ENABLE_SBU	GENMASK(6, 5)
> +#define FSA4480_ENABLE_USB	GENMASK(4, 3)
> +
> +#define FSA4480_SEL_SBU_REVERSE	GENMASK(6, 5)
> +#define FSA4480_SEL_USB		GENMASK(4, 3)
> +
> +struct fsa4480 {
> +	struct i2c_client *client;
> +
> +	/* used to serialize concurrent change requests */
> +	struct mutex lock;
> +
> +	struct typec_switch_dev *sw;
> +	struct typec_mux_dev *mux;
> +
> +	struct regmap *regmap;
> +
> +	u8 cur_enable;
> +	u8 cur_select;
> +};
> +
> +static const struct regmap_config fsa4480_regmap_config = {
> +	.reg_bits = 8,
> +	.val_bits = 8,
> +	.max_register = FSA4480_MAX_REGISTER,
> +	/* Accesses only done under fsa4480->lock */
> +	.disable_locking = true,
> +};
> +
> +static int fsa4480_switch_set(struct typec_switch_dev *sw,
> +			      enum typec_orientation orientation)
> +{
> +	struct fsa4480 *fsa = typec_switch_get_drvdata(sw);
> +	u8 new_sel;
> +
> +	mutex_lock(&fsa->lock);
> +	new_sel = FSA4480_SEL_USB;
> +	if (orientation == TYPEC_ORIENTATION_REVERSE)
> +		new_sel |= FSA4480_SEL_SBU_REVERSE;
> +
> +	if (new_sel == fsa->cur_select)
> +		goto out_unlock;
> +
> +	if (fsa->cur_enable & FSA4480_ENABLE_SBU) {
> +		/* Disable SBU output while re-configuring the switch */
> +		regmap_write(fsa->regmap, FSA4480_SWITCH_ENABLE,
> +			     fsa->cur_enable & ~FSA4480_ENABLE_SBU);
> +
> +		/* 35us to allow the SBU switch to turn off */
> +		usleep_range(35, 1000);
> +	}
> +
> +	regmap_write(fsa->regmap, FSA4480_SWITCH_SELECT, new_sel);
> +	fsa->cur_select = new_sel;
> +
> +	if (fsa->cur_enable & FSA4480_ENABLE_SBU) {
> +		regmap_write(fsa->regmap, FSA4480_SWITCH_ENABLE, fsa->cur_enable);
> +
> +		/* 15us to allow the SBU switch to turn on again */
> +		usleep_range(15, 1000);
> +	}
> +
> +out_unlock:
> +	mutex_unlock(&fsa->lock);
> +
> +	return 0;
> +}
> +
> +static int fsa4480_mux_set(struct typec_mux_dev *mux, struct typec_mux_state *state)
> +{
> +	struct fsa4480 *fsa = typec_mux_get_drvdata(mux);
> +	u8 new_enable;
> +
> +	mutex_lock(&fsa->lock);
> +
> +	new_enable = FSA4480_ENABLE_DEVICE | FSA4480_ENABLE_USB;
> +	if (state->mode >= TYPEC_DP_STATE_A)
> +		new_enable |= FSA4480_ENABLE_SBU;
> +
> +	if (new_enable == fsa->cur_enable)
> +		goto out_unlock;
> +
> +	regmap_write(fsa->regmap, FSA4480_SWITCH_ENABLE, new_enable);
> +	fsa->cur_enable = new_enable;
> +
> +	if (new_enable & FSA4480_ENABLE_SBU) {
> +		/* 15us to allow the SBU switch to turn off */
> +		usleep_range(15, 1000);
> +	}
> +
> +out_unlock:
> +	mutex_unlock(&fsa->lock);
> +
> +	return 0;
> +}
> +
> +static int fsa4480_probe(struct i2c_client *client)
> +{
> +	struct device *dev = &client->dev;
> +	struct typec_switch_desc sw_desc = { };
> +	struct typec_mux_desc mux_desc = { };
> +	struct fsa4480 *fsa;
> +
> +	fsa = devm_kzalloc(dev, sizeof(*fsa), GFP_KERNEL);
> +	if (!fsa)
> +		return -ENOMEM;
> +
> +	fsa->client = client;
> +	mutex_init(&fsa->lock);
> +
> +	fsa->regmap = devm_regmap_init_i2c(client, &fsa4480_regmap_config);
> +	if (IS_ERR(fsa->regmap))
> +		return dev_err_probe(dev, PTR_ERR(fsa->regmap), "failed to initialize regmap\n");
> +
> +	fsa->cur_enable = FSA4480_ENABLE_DEVICE | FSA4480_ENABLE_USB;
> +	fsa->cur_select = FSA4480_SEL_USB;
> +
> +	/* set default settings */
> +	regmap_write(fsa->regmap, FSA4480_SLOW_L, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_SLOW_R, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_SLOW_MIC, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_SLOW_SENSE, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_SLOW_GND, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_DELAY_L_R, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_DELAY_L_MIC, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_DELAY_L_SENSE, 0x00);
> +	regmap_write(fsa->regmap, FSA4480_DELAY_L_AGND, 0x09);
> +	regmap_write(fsa->regmap, FSA4480_SWITCH_SELECT, fsa->cur_select);
> +	regmap_write(fsa->regmap, FSA4480_SWITCH_ENABLE, fsa->cur_enable);
> +
> +	sw_desc.drvdata = fsa;
> +	sw_desc.fwnode = dev_fwnode(dev);
> +	sw_desc.set = fsa4480_switch_set;
> +
> +	fsa->sw = typec_switch_register(dev, &sw_desc);
> +	if (IS_ERR(fsa->sw))
> +		return dev_err_probe(dev, PTR_ERR(fsa->sw), "failed to register typec switch\n");
> +
> +	mux_desc.drvdata = fsa;
> +	mux_desc.fwnode = dev_fwnode(dev);
> +	mux_desc.set = fsa4480_mux_set;
> +
> +	fsa->mux = typec_mux_register(dev, &mux_desc);
> +	if (IS_ERR(fsa->mux)) {
> +		typec_switch_unregister(fsa->sw);
> +		return dev_err_probe(dev, PTR_ERR(fsa->mux), "failed to register typec mux\n");
> +	}
> +
> +	i2c_set_clientdata(client, fsa);
> +	return 0;
> +}
> +
> +static int fsa4480_remove(struct i2c_client *client)
> +{
> +	struct fsa4480 *fsa = i2c_get_clientdata(client);
> +
> +	typec_mux_unregister(fsa->mux);
> +	typec_switch_unregister(fsa->sw);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id fsa4480_table[] = {
> +	{ "fsa4480" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(i2c, fsa4480_table);
> +
> +static const struct of_device_id fsa4480_of_table[] = {
> +	{ .compatible = "fcs,fsa4480" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, fsa4480_of_table);
> +
> +static struct i2c_driver fsa4480_driver = {
> +	.driver = {
> +		.name = "fsa4480",
> +		.of_match_table = fsa4480_of_table,
> +	},
> +	.probe_new	= fsa4480_probe,
> +	.remove		= fsa4480_remove,
> +	.id_table	= fsa4480_table,
> +};
> +module_i2c_driver(fsa4480_driver);
> +
> +MODULE_DESCRIPTION("ON Semiconductor FSA4480 driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.35.1

-- 
heikki