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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * i2c support for Silicon Labs' CP2615 Digital Audio Bridge4 *5 * (c) 2021, Bence Csókás <bence98@sch.bme.hu>6 */7 8#include <linux/errno.h>9#include <linux/i2c.h>10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/string.h>13#include <linux/usb.h>14 15/** CP2615 I/O Protocol implementation */16 17#define CP2615_VID 0x10c418#define CP2615_PID 0xeac119 20#define IOP_EP_IN 0x8221#define IOP_EP_OUT 0x0222#define IOP_IFN 123#define IOP_ALTSETTING 224 25#define MAX_IOP_SIZE 6426#define MAX_IOP_PAYLOAD_SIZE (MAX_IOP_SIZE - 6)27#define MAX_I2C_SIZE (MAX_IOP_PAYLOAD_SIZE - 4)28 29enum cp2615_iop_msg_type {30 iop_GetAccessoryInfo = 0xD100,31 iop_AccessoryInfo = 0xA100,32 iop_GetPortConfiguration = 0xD203,33 iop_PortConfiguration = 0xA203,34 iop_DoI2cTransfer = 0xD400,35 iop_I2cTransferResult = 0xA400,36 iop_GetSerialState = 0xD501,37 iop_SerialState = 0xA50138};39 40struct __packed cp2615_iop_msg {41 __be16 preamble, length, msg;42 u8 data[MAX_IOP_PAYLOAD_SIZE];43};44 45#define PART_ID_A01 0x140046#define PART_ID_A02 0x150047 48struct __packed cp2615_iop_accessory_info {49 __be16 part_id, option_id, proto_ver;50};51 52struct __packed cp2615_i2c_transfer {53 u8 tag, i2caddr, read_len, write_len;54 u8 data[MAX_I2C_SIZE];55};56 57/* Possible values for struct cp2615_i2c_transfer_result.status */58enum cp2615_i2c_status {59 /* Writing to the internal EEPROM failed, because it is locked */60 CP2615_CFG_LOCKED = -6,61 /* read_len or write_len out of range */62 CP2615_INVALID_PARAM = -4,63 /* I2C target did not ACK in time */64 CP2615_TIMEOUT,65 /* I2C bus busy */66 CP2615_BUS_BUSY,67 /* I2C bus error (ie. target NAK'd the request) */68 CP2615_BUS_ERROR,69 CP2615_SUCCESS70};71 72struct __packed cp2615_i2c_transfer_result {73 u8 tag, i2caddr;74 s8 status;75 u8 read_len;76 u8 data[MAX_I2C_SIZE];77};78 79static int cp2615_init_iop_msg(struct cp2615_iop_msg *ret, enum cp2615_iop_msg_type msg,80 const void *data, size_t data_len)81{82 if (data_len > MAX_IOP_PAYLOAD_SIZE)83 return -EFBIG;84 85 if (!ret)86 return -EINVAL;87 88 ret->preamble = htons(0x2A2AU);89 ret->length = htons(data_len + 6);90 ret->msg = htons(msg);91 if (data && data_len)92 memcpy(&ret->data, data, data_len);93 return 0;94}95 96static int cp2615_init_i2c_msg(struct cp2615_iop_msg *ret, const struct cp2615_i2c_transfer *data)97{98 return cp2615_init_iop_msg(ret, iop_DoI2cTransfer, data, 4 + data->write_len);99}100 101/* Translates status codes to Linux errno's */102static int cp2615_check_status(enum cp2615_i2c_status status)103{104 switch (status) {105 case CP2615_SUCCESS:106 return 0;107 case CP2615_BUS_ERROR:108 return -ENXIO;109 case CP2615_BUS_BUSY:110 return -EAGAIN;111 case CP2615_TIMEOUT:112 return -ETIMEDOUT;113 case CP2615_INVALID_PARAM:114 return -EINVAL;115 case CP2615_CFG_LOCKED:116 return -EPERM;117 }118 /* Unknown error code */119 return -EPROTO;120}121 122/** Driver code */123 124static int125cp2615_i2c_send(struct usb_interface *usbif, struct cp2615_i2c_transfer *i2c_w)126{127 struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);128 struct usb_device *usbdev = interface_to_usbdev(usbif);129 int res = cp2615_init_i2c_msg(msg, i2c_w);130 131 if (!res)132 res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),133 msg, ntohs(msg->length), NULL, 0);134 kfree(msg);135 return res;136}137 138static int139cp2615_i2c_recv(struct usb_interface *usbif, unsigned char tag, void *buf)140{141 struct usb_device *usbdev = interface_to_usbdev(usbif);142 struct cp2615_iop_msg *msg;143 struct cp2615_i2c_transfer_result *i2c_r;144 int res;145 146 msg = kzalloc(sizeof(*msg), GFP_KERNEL);147 if (!msg)148 return -ENOMEM;149 150 res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN), msg,151 sizeof(struct cp2615_iop_msg), NULL, 0);152 if (res < 0) {153 kfree(msg);154 return res;155 }156 157 i2c_r = (struct cp2615_i2c_transfer_result *)&msg->data;158 if (msg->msg != htons(iop_I2cTransferResult) || i2c_r->tag != tag) {159 kfree(msg);160 return -EIO;161 }162 163 res = cp2615_check_status(i2c_r->status);164 if (!res)165 memcpy(buf, &i2c_r->data, i2c_r->read_len);166 167 kfree(msg);168 return res;169}170 171/* Checks if the IOP is functional by querying the part's ID */172static int cp2615_check_iop(struct usb_interface *usbif)173{174 struct cp2615_iop_msg *msg = kzalloc(sizeof(*msg), GFP_KERNEL);175 struct cp2615_iop_accessory_info *info = (struct cp2615_iop_accessory_info *)&msg->data;176 struct usb_device *usbdev = interface_to_usbdev(usbif);177 int res = cp2615_init_iop_msg(msg, iop_GetAccessoryInfo, NULL, 0);178 179 if (res)180 goto out;181 182 res = usb_bulk_msg(usbdev, usb_sndbulkpipe(usbdev, IOP_EP_OUT),183 msg, ntohs(msg->length), NULL, 0);184 if (res)185 goto out;186 187 res = usb_bulk_msg(usbdev, usb_rcvbulkpipe(usbdev, IOP_EP_IN),188 msg, sizeof(struct cp2615_iop_msg), NULL, 0);189 if (res)190 goto out;191 192 if (msg->msg != htons(iop_AccessoryInfo)) {193 res = -EIO;194 goto out;195 }196 197 switch (ntohs(info->part_id)) {198 case PART_ID_A01:199 dev_dbg(&usbif->dev, "Found A01 part. (WARNING: errata exists!)\n");200 break;201 case PART_ID_A02:202 dev_dbg(&usbif->dev, "Found good A02 part.\n");203 break;204 default:205 dev_warn(&usbif->dev, "Unknown part ID %04X\n", ntohs(info->part_id));206 }207 208out:209 kfree(msg);210 return res;211}212 213static int214cp2615_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)215{216 struct usb_interface *usbif = adap->algo_data;217 int i = 0, ret = 0;218 struct i2c_msg *msg;219 struct cp2615_i2c_transfer i2c_w = {0};220 221 dev_dbg(&usbif->dev, "Doing %d I2C transactions\n", num);222 223 for (; !ret && i < num; i++) {224 msg = &msgs[i];225 226 i2c_w.tag = 0xdd;227 i2c_w.i2caddr = i2c_8bit_addr_from_msg(msg);228 if (msg->flags & I2C_M_RD) {229 i2c_w.read_len = msg->len;230 i2c_w.write_len = 0;231 } else {232 i2c_w.read_len = 0;233 i2c_w.write_len = msg->len;234 memcpy(&i2c_w.data, msg->buf, i2c_w.write_len);235 }236 ret = cp2615_i2c_send(usbif, &i2c_w);237 if (ret)238 break;239 ret = cp2615_i2c_recv(usbif, i2c_w.tag, msg->buf);240 }241 if (ret < 0)242 return ret;243 return i;244}245 246static u32247cp2615_i2c_func(struct i2c_adapter *adap)248{249 return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;250}251 252static const struct i2c_algorithm cp2615_i2c_algo = {253 .xfer = cp2615_i2c_xfer,254 .functionality = cp2615_i2c_func,255};256 257/*258 * This chip has some limitations: one is that the USB endpoint259 * can only receive 64 bytes/transfer, that leaves 54 bytes for260 * the I2C transfer. On top of that, EITHER read_len OR write_len261 * may be zero, but not both. If both are non-zero, the adapter262 * issues a write followed by a read. And the chip does not263 * support repeated START between the write and read phases.264 */265static struct i2c_adapter_quirks cp2615_i2c_quirks = {266 .max_write_len = MAX_I2C_SIZE,267 .max_read_len = MAX_I2C_SIZE,268 .flags = I2C_AQ_COMB_WRITE_THEN_READ | I2C_AQ_NO_ZERO_LEN | I2C_AQ_NO_REP_START,269 .max_comb_1st_msg_len = MAX_I2C_SIZE,270 .max_comb_2nd_msg_len = MAX_I2C_SIZE271};272 273static void274cp2615_i2c_remove(struct usb_interface *usbif)275{276 struct i2c_adapter *adap = usb_get_intfdata(usbif);277 278 usb_set_intfdata(usbif, NULL);279 i2c_del_adapter(adap);280}281 282static int283cp2615_i2c_probe(struct usb_interface *usbif, const struct usb_device_id *id)284{285 int ret = 0;286 struct i2c_adapter *adap;287 struct usb_device *usbdev = interface_to_usbdev(usbif);288 289 ret = usb_set_interface(usbdev, IOP_IFN, IOP_ALTSETTING);290 if (ret)291 return ret;292 293 ret = cp2615_check_iop(usbif);294 if (ret)295 return ret;296 297 adap = devm_kzalloc(&usbif->dev, sizeof(struct i2c_adapter), GFP_KERNEL);298 if (!adap)299 return -ENOMEM;300 301 strscpy(adap->name, usbdev->serial, sizeof(adap->name));302 adap->owner = THIS_MODULE;303 adap->dev.parent = &usbif->dev;304 adap->dev.of_node = usbif->dev.of_node;305 adap->timeout = HZ;306 adap->algo = &cp2615_i2c_algo;307 adap->quirks = &cp2615_i2c_quirks;308 adap->algo_data = usbif;309 310 ret = i2c_add_adapter(adap);311 if (ret)312 return ret;313 314 usb_set_intfdata(usbif, adap);315 return 0;316}317 318static const struct usb_device_id id_table[] = {319 { USB_DEVICE_INTERFACE_NUMBER(CP2615_VID, CP2615_PID, IOP_IFN) },320 { }321};322 323MODULE_DEVICE_TABLE(usb, id_table);324 325static struct usb_driver cp2615_i2c_driver = {326 .name = "i2c-cp2615",327 .probe = cp2615_i2c_probe,328 .disconnect = cp2615_i2c_remove,329 .id_table = id_table,330};331 332module_usb_driver(cp2615_i2c_driver);333 334MODULE_AUTHOR("Bence Csókás <bence98@sch.bme.hu>");335MODULE_DESCRIPTION("CP2615 I2C bus driver");336MODULE_LICENSE("GPL");337