i2c: cp2615: add i2c driver for Silicon Labs' CP2615 Digital Audio Bridge (4a769542) · Commits · EulixOS / Software / Kernel

MAINTAINERS

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		@@ -4585,6 +4585,11 @@ F: drivers/counter/
		F: include/linux/counter.h
		F: include/linux/counter_enum.h

		CP2615 I2C DRIVER
		M: Bence Csókás <bence98@sch.bme.hu>
		S: Maintained
		F: drivers/i2c/busses/i2c-cp2615.c

		CPMAC ETHERNET DRIVER
		M: Florian Fainelli <f.fainelli@gmail.com>
		L: netdev@vger.kernel.org

drivers/i2c/busses/Kconfig

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		@@ -1199,6 +1199,16 @@ config I2C_DLN2
		This driver can also be built as a module. If so, the module
		will be called i2c-dln2.

		config I2C_CP2615
		tristate "Silicon Labs CP2615 USB sound card and I2C adapter"
		depends on USB
		help
		If you say yes to this option, support will be included for Silicon
		Labs CP2615's I2C interface.

		This driver can also be built as a module. If so, the module
		will be called i2c-cp2615.

		config I2C_PARPORT
		tristate "Parallel port adapter"
		depends on PARPORT

drivers/i2c/busses/Makefile

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		@@ -123,6 +123,7 @@ obj-$(CONFIG_I2C_RCAR) += i2c-rcar.o
		# External I2C/SMBus adapter drivers
		obj-$(CONFIG_I2C_DIOLAN_U2C) += i2c-diolan-u2c.o
		obj-$(CONFIG_I2C_DLN2) += i2c-dln2.o
		obj-$(CONFIG_I2C_CP2615) += i2c-cp2615.o
		obj-$(CONFIG_I2C_PARPORT) += i2c-parport.o
		obj-$(CONFIG_I2C_ROBOTFUZZ_OSIF) += i2c-robotfuzz-osif.o
		obj-$(CONFIG_I2C_TAOS_EVM) += i2c-taos-evm.o

drivers/i2c/busses/i2c-cp2615.c

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		// SPDX-License-Identifier: GPL-2.0-or-later
		/*
		* i2c support for Silicon Labs' CP2615 Digital Audio Bridge
		*
		* (c) 2021, Bence Csókás <bence98@sch.bme.hu>
		*/

		#include <linux/errno.h>
		#include <linux/i2c.h>
		#include <linux/kernel.h>
		#include <linux/module.h>
		#include <linux/string.h>
		#include <linux/usb.h>

		/** CP2615 I/O Protocol implementation */

		#define CP2615_VID 0x10c4
		#define CP2615_PID 0xeac1

		#define IOP_EP_IN 0x82
		#define IOP_EP_OUT 0x02
		#define IOP_IFN 1
		#define IOP_ALTSETTING 2

		#define MAX_IOP_SIZE 64
		#define MAX_IOP_PAYLOAD_SIZE (MAX_IOP_SIZE - 6)
		#define MAX_I2C_SIZE (MAX_IOP_PAYLOAD_SIZE - 4)

		enum cp2615_iop_msg_type {
		iop_GetAccessoryInfo = 0xD100,
		iop_AccessoryInfo = 0xA100,
		iop_GetPortConfiguration = 0xD203,
		iop_PortConfiguration = 0xA203,
		iop_DoI2cTransfer = 0xD400,
		iop_I2cTransferResult = 0xA400,
		iop_GetSerialState = 0xD501,
		iop_SerialState = 0xA501
		};

		struct __packed cp2615_iop_msg {
		__be16 preamble, length, msg;
		u8 data[MAX_IOP_PAYLOAD_SIZE];
		};

		#define PART_ID_A01 0x1400
		#define PART_ID_A02 0x1500

		struct __packed cp2615_iop_accessory_info {
		__be16 part_id, option_id, proto_ver;
		};

		struct __packed cp2615_i2c_transfer {
		u8 tag, i2caddr, read_len, write_len;
		u8 data[MAX_I2C_SIZE];
		};

		/* Possible values for struct cp2615_i2c_transfer_result.status */
		enum cp2615_i2c_status {
		/* Writing to the internal EEPROM failed, because it is locked */
		CP2615_CFG_LOCKED = -6,
		/* read_len or write_len out of range */
		CP2615_INVALID_PARAM = -4,
		/* I2C slave did not ACK in time */
		CP2615_TIMEOUT,
		/* I2C bus busy */
		CP2615_BUS_BUSY,
		/* I2C bus error (ie. device NAK'd the request) */
		CP2615_BUS_ERROR,
		CP2615_SUCCESS
		};

		struct __packed cp2615_i2c_transfer_result {
		u8 tag, i2caddr;
		s8 status;
		u8 read_len;
		u8 data[MAX_I2C_SIZE];
		};

		static int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,
		const void *data, size_t data_len)
		{
		if (data_len > MAX_IOP_PAYLOAD_SIZE)
		return -EFBIG;

		if (!ret)
		return -EINVAL;

		ret->preamble = 0x2A2A;
		ret->length = htons(data_len + 6);
		ret->msg = htons(msg);
		if (data && data_len)
		memcpy(&ret->data, data, data_len);
		return 0;
		}

		static int cp2615_init_i2c_msg(struct cp2615_iop_msg ret, const struct cp2615_i2c_transfer data)
		{
		return cp2615_init_iop_msg(ret, iop_DoI2cTransfer, data, 4 + data->write_len);
		}

		/* Translates status codes to Linux errno's */
		static int cp2615_check_status(enum cp2615_i2c_status status)
		{
		switch (status) {
		case CP2615_SUCCESS:
		return 0;
		case CP2615_BUS_ERROR:
		return -ENXIO;
		case CP2615_BUS_BUSY:
		return -EAGAIN;
		case CP2615_TIMEOUT:
		return -ETIMEDOUT;
		case CP2615_INVALID_PARAM:
		return -EINVAL;
		case CP2615_CFG_LOCKED:
		return -EPERM;
		}
		/* Unknown error code */
		return -EPROTO;
		}

		/** Driver code */

		static int
		cp2615_i2c_send(struct usb_interface usbif, struct cp2615_i2c_transfer i2c_w)
		{
		struct cp2615_iop_msg msg = kzalloc(sizeof(msg), GFP_KERNEL);
		struct usb_device *usbdev = interface_to_usbdev(usbif);
		int res = cp2615_init_i2c_msg(msg, i2c_w);

		if (!res)
		res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
		msg, ntohs(msg->length), NULL, 0);
		kfree(msg);
		return res;
		}

		static int
		cp2615_i2c_recv(struct usb_interface usbif, unsigned char tag, void buf)
		{
		struct cp2615_iop_msg msg = kzalloc(sizeof(msg), GFP_KERNEL);
		struct cp2615_i2c_transfer_result i2c_r = (struct cp2615_i2c_transfer_result )&msg->data;
		struct usb_device *usbdev = interface_to_usbdev(usbif);
		int res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
		msg, sizeof(struct cp2615_iop_msg), NULL, 0);

		if (res < 0) {
		kfree(msg);
		return res;
		}

		if (msg->msg != htons(iop_I2cTransferResult) \|\| i2c_r->tag != tag) {
		kfree(msg);
		return -EIO;
		}

		res = cp2615_check_status(i2c_r->status);
		if (!res)
		memcpy(buf, &i2c_r->data, i2c_r->read_len);

		kfree(msg);
		return res;
		}

		/* Checks if the IOP is functional by querying the part's ID */
		static int cp2615_check_iop(struct usb_interface *usbif)
		{
		struct cp2615_iop_msg msg = kzalloc(sizeof(msg), GFP_KERNEL);
		struct cp2615_iop_accessory_info info = (struct cp2615_iop_accessory_info )&msg->data;
		struct usb_device *usbdev = interface_to_usbdev(usbif);
		int res = cp2615_init_iop_msg(msg, iop_GetAccessoryInfo, NULL, 0);

		if (res)
		goto out;

		res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
		msg, ntohs(msg->length), NULL, 0);
		if (res)
		goto out;

		res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
		msg, sizeof(struct cp2615_iop_msg), NULL, 0);
		if (res)
		goto out;

		if (msg->msg != htons(iop_AccessoryInfo)) {
		res = -EIO;
		goto out;
		}

		switch (ntohs(info->part_id)) {
		case PART_ID_A01:
		dev_dbg(&usbif->dev, "Found A01 part. (WARNING: errata exists!)\n");
		break;
		case PART_ID_A02:
		dev_dbg(&usbif->dev, "Found good A02 part.\n");
		break;
		default:
		dev_warn(&usbif->dev, "Unknown part ID %04X\n", ntohs(info->part_id));
		}

		out:
		kfree(msg);
		return res;
		}

		static int
		cp2615_i2c_master_xfer(struct i2c_adapter adap, struct i2c_msg msgs, int num)
		{
		struct usb_interface *usbif = adap->algo_data;
		int i = 0, ret = 0;
		struct i2c_msg *msg;
		struct cp2615_i2c_transfer i2c_w = {0};

		dev_dbg(&usbif->dev, "Doing %d I2C transactions\n", num);

		for (; !ret && i < num; i++) {
		msg = &msgs[i];

		i2c_w.tag = 0xdd;
		i2c_w.i2caddr = i2c_8bit_addr_from_msg(msg);
		if (msg->flags & I2C_M_RD) {
		i2c_w.read_len = msg->len;
		i2c_w.write_len = 0;
		} else {
		i2c_w.read_len = 0;
		i2c_w.write_len = msg->len;
		memcpy(&i2c_w.data, msg->buf, i2c_w.write_len);
		}
		ret = cp2615_i2c_send(usbif, &i2c_w);
		if (ret)
		break;
		ret = cp2615_i2c_recv(usbif, i2c_w.tag, msg->buf);
		}
		if (ret < 0)
		return ret;
		return i;
		}

		static u32
		cp2615_i2c_func(struct i2c_adapter *adap)
		{
		return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
		}

		static const struct i2c_algorithm cp2615_i2c_algo = {
		.master_xfer = cp2615_i2c_master_xfer,
		.functionality = cp2615_i2c_func,
		};

		/*
		* This chip has some limitations: one is that the USB endpoint
		* can only receive 64 bytes/transfer, that leaves 54 bytes for
		* the I2C transfer. On top of that, EITHER read_len OR write_len
		* may be zero, but not both. If both are non-zero, the adapter
		* issues a write followed by a read. And the chip does not
		* support repeated START between the write and read phases.
		*/
		static struct i2c_adapter_quirks cp2615_i2c_quirks = {
		.max_write_len = MAX_I2C_SIZE,
		.max_read_len = MAX_I2C_SIZE,
		.flags = I2C_AQ_COMB_WRITE_THEN_READ \| I2C_AQ_NO_ZERO_LEN \| I2C_AQ_NO_REP_START,
		.max_comb_1st_msg_len = MAX_I2C_SIZE,
		.max_comb_2nd_msg_len = MAX_I2C_SIZE
		};

		static void
		cp2615_i2c_remove(struct usb_interface *usbif)
		{
		struct i2c_adapter *adap = usb_get_intfdata(usbif);

		usb_set_intfdata(usbif, NULL);
		i2c_del_adapter(adap);
		}

		static int
		cp2615_i2c_probe(struct usb_interface usbif, const struct usb_device_id id)
		{
		int ret = 0;
		struct i2c_adapter *adap;
		struct usb_device *usbdev = interface_to_usbdev(usbif);

		ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING);
		if (ret)
		return ret;

		ret = cp2615_check_iop(usbif);
		if (ret)
		return ret;

		adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
		if (!adap)
		return -ENOMEM;

		strncpy(adap->name, usbdev->serial, sizeof(adap->name) - 1);
		adap->owner = THIS_MODULE;
		adap->dev.parent = &usbif->dev;
		adap->dev.of_node = usbif->dev.of_node;
		adap->timeout = HZ;
		adap->algo = &cp2615_i2c_algo;
		adap->quirks = &cp2615_i2c_quirks;
		adap->algo_data = usbif;

		ret = i2c_add_adapter(adap);
		if (ret)
		return ret;

		usb_set_intfdata(usbif, adap);
		return 0;
		}

		static const struct usb_device_id id_table[] = {
		{ USB_DEVICE_INTERFACE_NUMBER(CP2615_VID, CP2615_PID, IOP_IFN) },
		{ }
		};

		MODULE_DEVICE_TABLE(usb, id_table);

		static struct usb_driver cp2615_i2c_driver = {
		.name = "i2c-cp2615",
		.probe = cp2615_i2c_probe,
		.disconnect = cp2615_i2c_remove,
		.id_table = id_table,
		};

		module_usb_driver(cp2615_i2c_driver);

		MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
		MODULE_DESCRIPTION("CP2615 I2C bus driver");
		MODULE_LICENSE("GPL");