337 lines
8.0 KiB
C
337 lines
8.0 KiB
C
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* i2c support for Silicon Labs' CP2615 Digital Audio Bridge
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*
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* (c) 2021, Bence Csókás <bence98@sch.bme.hu>
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*/
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#include <linux/errno.h>
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#include <linux/i2c.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/string.h>
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#include <linux/usb.h>
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/** CP2615 I/O Protocol implementation */
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#define CP2615_VID 0x10c4
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#define CP2615_PID 0xeac1
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#define IOP_EP_IN 0x82
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#define IOP_EP_OUT 0x02
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#define IOP_IFN 1
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#define IOP_ALTSETTING 2
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#define MAX_IOP_SIZE 64
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#define MAX_IOP_PAYLOAD_SIZE (MAX_IOP_SIZE - 6)
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#define MAX_I2C_SIZE (MAX_IOP_PAYLOAD_SIZE - 4)
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enum cp2615_iop_msg_type {
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iop_GetAccessoryInfo = 0xD100,
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iop_AccessoryInfo = 0xA100,
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iop_GetPortConfiguration = 0xD203,
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iop_PortConfiguration = 0xA203,
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iop_DoI2cTransfer = 0xD400,
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iop_I2cTransferResult = 0xA400,
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iop_GetSerialState = 0xD501,
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iop_SerialState = 0xA501
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};
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struct __packed cp2615_iop_msg {
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__be16 preamble, length, msg;
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u8 data[MAX_IOP_PAYLOAD_SIZE];
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};
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#define PART_ID_A01 0x1400
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#define PART_ID_A02 0x1500
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struct __packed cp2615_iop_accessory_info {
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__be16 part_id, option_id, proto_ver;
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};
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struct __packed cp2615_i2c_transfer {
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u8 tag, i2caddr, read_len, write_len;
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u8 data[MAX_I2C_SIZE];
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};
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/* Possible values for struct cp2615_i2c_transfer_result.status */
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enum cp2615_i2c_status {
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/* Writing to the internal EEPROM failed, because it is locked */
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CP2615_CFG_LOCKED = -6,
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/* read_len or write_len out of range */
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CP2615_INVALID_PARAM = -4,
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/* I2C slave did not ACK in time */
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CP2615_TIMEOUT,
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/* I2C bus busy */
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CP2615_BUS_BUSY,
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/* I2C bus error (ie. device NAK'd the request) */
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CP2615_BUS_ERROR,
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CP2615_SUCCESS
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};
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struct __packed cp2615_i2c_transfer_result {
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u8 tag, i2caddr;
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s8 status;
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u8 read_len;
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u8 data[MAX_I2C_SIZE];
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};
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static int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,
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const void *data, size_t data_len)
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{
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if (data_len > MAX_IOP_PAYLOAD_SIZE)
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return -EFBIG;
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if (!ret)
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return -EINVAL;
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ret->preamble = 0x2A2A;
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ret->length = htons(data_len + 6);
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ret->msg = htons(msg);
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if (data && data_len)
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memcpy(&ret->data, data, data_len);
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return 0;
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}
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static int cp2615_init_i2c_msg(struct cp2615_iop_msg *ret, const struct cp2615_i2c_transfer *data)
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{
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return cp2615_init_iop_msg(ret, iop_DoI2cTransfer, data, 4 + data->write_len);
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}
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/* Translates status codes to Linux errno's */
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static int cp2615_check_status(enum cp2615_i2c_status status)
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{
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switch (status) {
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case CP2615_SUCCESS:
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return 0;
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case CP2615_BUS_ERROR:
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return -ENXIO;
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case CP2615_BUS_BUSY:
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return -EAGAIN;
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case CP2615_TIMEOUT:
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return -ETIMEDOUT;
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case CP2615_INVALID_PARAM:
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return -EINVAL;
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case CP2615_CFG_LOCKED:
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return -EPERM;
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}
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/* Unknown error code */
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return -EPROTO;
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}
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/** Driver code */
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static int
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cp2615_i2c_send(struct usb_interface *usbif, struct cp2615_i2c_transfer *i2c_w)
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{
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struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
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struct usb_device *usbdev = interface_to_usbdev(usbif);
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int res = cp2615_init_i2c_msg(msg, i2c_w);
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if (!res)
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res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
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msg, ntohs(msg->length), NULL, 0);
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kfree(msg);
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return res;
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}
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static int
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cp2615_i2c_recv(struct usb_interface *usbif, unsigned char tag, void *buf)
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{
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struct usb_device *usbdev = interface_to_usbdev(usbif);
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struct cp2615_iop_msg *msg;
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struct cp2615_i2c_transfer_result *i2c_r;
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int res;
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msg = kzalloc(sizeof(*msg), GFP_KERNEL);
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if (!msg)
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return -ENOMEM;
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res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN), msg,
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sizeof(struct cp2615_iop_msg), NULL, 0);
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if (res < 0) {
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kfree(msg);
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return res;
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}
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i2c_r = (struct cp2615_i2c_transfer_result *)&msg->data;
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if (msg->msg != htons(iop_I2cTransferResult) || i2c_r->tag != tag) {
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kfree(msg);
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return -EIO;
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}
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res = cp2615_check_status(i2c_r->status);
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if (!res)
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memcpy(buf, &i2c_r->data, i2c_r->read_len);
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kfree(msg);
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return res;
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}
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/* Checks if the IOP is functional by querying the part's ID */
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static int cp2615_check_iop(struct usb_interface *usbif)
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{
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struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);
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struct cp2615_iop_accessory_info *info = (struct cp2615_iop_accessory_info *)&msg->data;
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struct usb_device *usbdev = interface_to_usbdev(usbif);
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int res = cp2615_init_iop_msg(msg, iop_GetAccessoryInfo, NULL, 0);
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if (res)
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goto out;
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res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),
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msg, ntohs(msg->length), NULL, 0);
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if (res)
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goto out;
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res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),
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msg, sizeof(struct cp2615_iop_msg), NULL, 0);
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if (res)
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goto out;
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if (msg->msg != htons(iop_AccessoryInfo)) {
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res = -EIO;
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goto out;
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}
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switch (ntohs(info->part_id)) {
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case PART_ID_A01:
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dev_dbg(&usbif->dev, "Found A01 part. (WARNING: errata exists!)\n");
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break;
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case PART_ID_A02:
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dev_dbg(&usbif->dev, "Found good A02 part.\n");
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break;
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default:
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dev_warn(&usbif->dev, "Unknown part ID %04X\n", ntohs(info->part_id));
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}
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out:
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kfree(msg);
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return res;
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}
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static int
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cp2615_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
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{
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struct usb_interface *usbif = adap->algo_data;
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int i = 0, ret = 0;
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struct i2c_msg *msg;
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struct cp2615_i2c_transfer i2c_w = {0};
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dev_dbg(&usbif->dev, "Doing %d I2C transactions\n", num);
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for (; !ret && i < num; i++) {
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msg = &msgs[i];
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i2c_w.tag = 0xdd;
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i2c_w.i2caddr = i2c_8bit_addr_from_msg(msg);
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if (msg->flags & I2C_M_RD) {
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i2c_w.read_len = msg->len;
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i2c_w.write_len = 0;
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} else {
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i2c_w.read_len = 0;
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i2c_w.write_len = msg->len;
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memcpy(&i2c_w.data, msg->buf, i2c_w.write_len);
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}
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ret = cp2615_i2c_send(usbif, &i2c_w);
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if (ret)
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break;
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ret = cp2615_i2c_recv(usbif, i2c_w.tag, msg->buf);
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}
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if (ret < 0)
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return ret;
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return i;
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}
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static u32
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cp2615_i2c_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm cp2615_i2c_algo = {
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.master_xfer = cp2615_i2c_master_xfer,
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.functionality = cp2615_i2c_func,
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};
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/*
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* This chip has some limitations: one is that the USB endpoint
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* can only receive 64 bytes/transfer, that leaves 54 bytes for
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* the I2C transfer. On top of that, EITHER read_len OR write_len
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* may be zero, but not both. If both are non-zero, the adapter
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* issues a write followed by a read. And the chip does not
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* support repeated START between the write and read phases.
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*/
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static struct i2c_adapter_quirks cp2615_i2c_quirks = {
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.max_write_len = MAX_I2C_SIZE,
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.max_read_len = MAX_I2C_SIZE,
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.flags = I2C_AQ_COMB_WRITE_THEN_READ | I2C_AQ_NO_ZERO_LEN | I2C_AQ_NO_REP_START,
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.max_comb_1st_msg_len = MAX_I2C_SIZE,
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.max_comb_2nd_msg_len = MAX_I2C_SIZE
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};
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static void
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cp2615_i2c_remove(struct usb_interface *usbif)
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{
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struct i2c_adapter *adap = usb_get_intfdata(usbif);
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usb_set_intfdata(usbif, NULL);
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i2c_del_adapter(adap);
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}
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static int
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cp2615_i2c_probe(struct usb_interface *usbif, const struct usb_device_id *id)
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{
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int ret = 0;
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struct i2c_adapter *adap;
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struct usb_device *usbdev = interface_to_usbdev(usbif);
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ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING);
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if (ret)
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return ret;
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ret = cp2615_check_iop(usbif);
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if (ret)
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return ret;
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adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
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if (!adap)
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return -ENOMEM;
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strncpy(adap->name, usbdev->serial, sizeof(adap->name) - 1);
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adap->owner = THIS_MODULE;
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adap->dev.parent = &usbif->dev;
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adap->dev.of_node = usbif->dev.of_node;
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adap->timeout = HZ;
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adap->algo = &cp2615_i2c_algo;
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adap->quirks = &cp2615_i2c_quirks;
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adap->algo_data = usbif;
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ret = i2c_add_adapter(adap);
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if (ret)
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return ret;
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usb_set_intfdata(usbif, adap);
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return 0;
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}
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static const struct usb_device_id id_table[] = {
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{ USB_DEVICE_INTERFACE_NUMBER(CP2615_VID, CP2615_PID, IOP_IFN) },
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{ }
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};
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MODULE_DEVICE_TABLE(usb, id_table);
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static struct usb_driver cp2615_i2c_driver = {
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.name = "i2c-cp2615",
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.probe = cp2615_i2c_probe,
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.disconnect = cp2615_i2c_remove,
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.id_table = id_table,
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};
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module_usb_driver(cp2615_i2c_driver);
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MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");
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MODULE_DESCRIPTION("CP2615 I2C bus driver");
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MODULE_LICENSE("GPL");
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