diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-cp2615.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-cp2615.c | 336 |
1 files changed, 336 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-cp2615.c b/drivers/i2c/busses/i2c-cp2615.c new file mode 100644 index 000000000..3ded28632 --- /dev/null +++ b/drivers/i2c/busses/i2c-cp2615.c @@ -0,0 +1,336 @@ +// 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 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_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"); |