// SPDX-License-Identifier: GPL-2.0-or-later
/*
* i2c support for Silicon Labs' CP2615 Digital Audio Bridge
*
* (c) 2021, Bence Csókás <[email protected]>
*/
#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 target did not ACK in time */
CP2615_TIMEOUT,
/* I2C bus busy */
CP2615_BUS_BUSY,
/* I2C bus error (ie. target 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 = htons(0x2A2AU);
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 usb_device *usbdev = interface_to_usbdev(usbif);
struct cp2615_iop_msg *msg;
struct cp2615_i2c_transfer_result *i2c_r;
int res;
msg = kzalloc(sizeof(*msg), GFP_KERNEL);
if (!msg)
return -ENOMEM;
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;
}
i2c_r = (struct cp2615_i2c_transfer_result *)&msg->data;
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_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 = {
.xfer = cp2615_i2c_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;
strscpy(adap->name, usbdev->serial, sizeof(adap->name));
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 <[email protected]>");
MODULE_DESCRIPTION("CP2615 I2C bus driver");
MODULE_LICENSE("GPL");
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