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Adding i2c-cp2615: i2c support for Silicon Labs' CP2615 Digital Audio…
… Bridge Signed-off-by: Bence Csókás <bence98@sch.bme.hu>
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/* SPDX-License-Identifier: GPL-2.0 */ | ||
/* | ||
* i2c support for Silicon Labs' CP2615 Digital Audio Bridge | ||
* | ||
* (c) 2021, Bence Csókás <bence98@sch.bme.hu> | ||
*/ | ||
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#include <linux/string.h> | ||
#include <linux/kernel.h> | ||
#include <linux/errno.h> | ||
#include <linux/i2c.h> | ||
#include <linux/usb.h> | ||
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/** CP2615 I/O Protocol implementation */ | ||
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#define CP2615_VID 0x10c4 | ||
#define CP2615_PID 0xeac1 | ||
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#define IOP_EP_IN 0x82 | ||
#define IOP_EP_OUT 0x02 | ||
#define IOP_IFN 1 | ||
#define IOP_ALTSETTING 2 | ||
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#define MAX_IOP_SIZE 64 | ||
#define MAX_IOP_PAYLOAD_SIZE MAX_IOP_SIZE-6 | ||
#define MAX_I2C_SIZE MAX_IOP_PAYLOAD_SIZE-4 | ||
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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 | ||
}; | ||
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struct cp2615_iop_msg { | ||
uint16_t preamble, length, msg; | ||
uint8_t data[MAX_IOP_PAYLOAD_SIZE]; | ||
}; | ||
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#define PART_ID_A01 0x1400 | ||
#define PART_ID_A02 0x1500 | ||
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struct cp2615_iop_accessory_info { | ||
uint16_t part_id, option_id, proto_ver; | ||
}; | ||
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struct cp2615_i2c_transfer { | ||
uint8_t tag, i2caddr, read_len, write_len; | ||
uint8_t data[MAX_I2C_SIZE]; | ||
}; | ||
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/** Possible values for struct cp2615_i2c_transfer_result.status | ||
* | ||
* Values extracted from the USBXpress(r) SDK | ||
*/ | ||
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 | ||
}; | ||
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struct cp2615_i2c_transfer_result { | ||
uint8_t tag, i2caddr; | ||
int8_t status; | ||
uint8_t read_len; | ||
uint8_t data[MAX_I2C_SIZE]; | ||
}; | ||
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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; | ||
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if (ret) { | ||
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; | ||
} else { | ||
return -EINVAL; | ||
} | ||
} | ||
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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); | ||
} | ||
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/* Translates status codes to Linux errno's */ | ||
int cp2615_check_status(enum cp2615_i2c_status status) | ||
{ | ||
switch (status) { | ||
case CP2615_SUCCESS: | ||
return 0; | ||
case CP2615_BUS_ERROR: | ||
return -ECOMM; | ||
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; | ||
} | ||
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static int | ||
cp2615_i2c_send(struct usb_interface *usbif, struct cp2615_i2c_transfer *i2c_w) | ||
{ | ||
struct cp2615_iop_msg *msg = kzalloc(sizeof(struct cp2615_iop_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; | ||
} | ||
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static int | ||
cp2615_i2c_recv(struct usb_interface *usbif, unsigned char tag, void *buf) | ||
{ | ||
struct cp2615_iop_msg *msg = kzalloc(sizeof(struct cp2615_iop_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) | ||
return res; | ||
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if (msg->msg != htons(iop_I2cTransferResult) || i2c_r->tag != tag) | ||
return -EIO; | ||
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res = cp2615_check_status(i2c_r->status); | ||
if (res < 0) | ||
return res; | ||
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memcpy(buf, &i2c_r->data, i2c_r->read_len); | ||
kfree(msg); | ||
return 0; | ||
} | ||
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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); | ||
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for(; !ret && i < num; i++) { | ||
msg = &msgs[i]; | ||
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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; | ||
} | ||
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static u32 | ||
cp2615_i2c_func(struct i2c_adapter *adap) | ||
{ | ||
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; | ||
} | ||
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static const struct i2c_algorithm cp2615_i2c_algo = { | ||
.master_xfer = cp2615_i2c_master_xfer, | ||
.functionality = cp2615_i2c_func, | ||
}; | ||
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/* | ||
* 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. | ||
* | ||
* FIXME: There in no quirk flag for specifying that the adapter | ||
* does not support empty transfers, or that it cannot emit a | ||
* START condition between the combined phases. | ||
*/ | ||
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, | ||
.max_comb_1st_msg_len = MAX_I2C_SIZE, | ||
.max_comb_2nd_msg_len = MAX_I2C_SIZE | ||
}; | ||
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static void | ||
cp2615_i2c_remove(struct usb_interface *usbif) | ||
{ | ||
struct i2c_adapter *adap = usb_get_intfdata(usbif); | ||
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usb_set_intfdata(usbif, NULL); | ||
i2c_del_adapter(adap); | ||
} | ||
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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); | ||
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ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING); | ||
if (ret) | ||
return ret; | ||
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adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL); | ||
if (!adap) | ||
return -ENOMEM; | ||
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strncpy(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; | ||
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ret = i2c_add_adapter(adap); | ||
if (ret) | ||
return ret; | ||
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usb_set_intfdata(usbif, adap); | ||
return ret; | ||
} | ||
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static const struct usb_device_id id_table[] = { | ||
{ USB_DEVICE(CP2615_VID, CP2615_PID) }, | ||
{ } | ||
}; | ||
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MODULE_DEVICE_TABLE(usb, id_table); | ||
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static struct usb_driver cp2615_i2c_driver = { | ||
.name = "i2c-cp2615", | ||
.probe = cp2615_i2c_probe, | ||
.disconnect = cp2615_i2c_remove, | ||
.id_table = id_table, | ||
}; | ||
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module_usb_driver(cp2615_i2c_driver); | ||
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MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>"); | ||
MODULE_DESCRIPTION("CP2615 I2C bus driver"); | ||
MODULE_LICENSE("GPL"); |