// SPDX-License-Identifier: GPL-2.0-only /* i2c-isch.c - Linux kernel driver for Intel SCH chipset SMBus - Based on i2c-piix4.c Copyright (c) 1998 - 2002 Frodo Looijaard and Philip Edelbrock - Intel SCH support Copyright (c) 2007 - 2008 Jacob Jun Pan */ /* Supports: Intel SCH chipsets (AF82US15W, AF82US15L, AF82UL11L) Note: we assume there can only be one device, with one SMBus interface. */ #include #include #include #include #include #include #include #include /* SCH SMBus address offsets */ #define SMBHSTCNT (0 + sch_smba) #define SMBHSTSTS (1 + sch_smba) #define SMBHSTCLK (2 + sch_smba) #define SMBHSTADD (4 + sch_smba) /* TSA */ #define SMBHSTCMD (5 + sch_smba) #define SMBHSTDAT0 (6 + sch_smba) #define SMBHSTDAT1 (7 + sch_smba) #define SMBBLKDAT (0x20 + sch_smba) /* Other settings */ #define MAX_RETRIES 5000 /* I2C constants */ #define SCH_QUICK 0x00 #define SCH_BYTE 0x01 #define SCH_BYTE_DATA 0x02 #define SCH_WORD_DATA 0x03 #define SCH_BLOCK_DATA 0x05 static unsigned short sch_smba; static struct i2c_adapter sch_adapter; static int backbone_speed = 33000; /* backbone speed in kHz */ module_param(backbone_speed, int, S_IRUSR | S_IWUSR); MODULE_PARM_DESC(backbone_speed, "Backbone speed in kHz, (default = 33000)"); /* * Start the i2c transaction -- the i2c_access will prepare the transaction * and this function will execute it. * return 0 for success and others for failure. */ static int sch_transaction(void) { int temp; int result = 0; int retries = 0; dev_dbg(&sch_adapter.dev, "Transaction (pre): CNT=%02x, CMD=%02x, " "ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT), inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0), inb(SMBHSTDAT1)); /* Make sure the SMBus host is ready to start transmitting */ temp = inb(SMBHSTSTS) & 0x0f; if (temp) { /* Can not be busy since we checked it in sch_access */ if (temp & 0x01) { dev_dbg(&sch_adapter.dev, "Completion (%02x). " "Clear...\n", temp); } if (temp & 0x06) { dev_dbg(&sch_adapter.dev, "SMBus error (%02x). " "Resetting...\n", temp); } outb(temp, SMBHSTSTS); temp = inb(SMBHSTSTS) & 0x0f; if (temp) { dev_err(&sch_adapter.dev, "SMBus is not ready: (%02x)\n", temp); return -EAGAIN; } } /* start the transaction by setting bit 4 */ outb(inb(SMBHSTCNT) | 0x10, SMBHSTCNT); do { usleep_range(100, 200); temp = inb(SMBHSTSTS) & 0x0f; } while ((temp & 0x08) && (retries++ < MAX_RETRIES)); /* If the SMBus is still busy, we give up */ if (retries > MAX_RETRIES) { dev_err(&sch_adapter.dev, "SMBus Timeout!\n"); result = -ETIMEDOUT; } else if (temp & 0x04) { result = -EIO; dev_dbg(&sch_adapter.dev, "Bus collision! SMBus may be " "locked until next hard reset. (sorry!)\n"); /* Clock stops and slave is stuck in mid-transmission */ } else if (temp & 0x02) { result = -EIO; dev_err(&sch_adapter.dev, "Error: no response!\n"); } else if (temp & 0x01) { dev_dbg(&sch_adapter.dev, "Post complete!\n"); outb(temp, SMBHSTSTS); temp = inb(SMBHSTSTS) & 0x07; if (temp & 0x06) { /* Completion clear failed */ dev_dbg(&sch_adapter.dev, "Failed reset at end of " "transaction (%02x), Bus error!\n", temp); } } else { result = -ENXIO; dev_dbg(&sch_adapter.dev, "No such address.\n"); } dev_dbg(&sch_adapter.dev, "Transaction (post): CNT=%02x, CMD=%02x, " "ADD=%02x, DAT0=%02x, DAT1=%02x\n", inb(SMBHSTCNT), inb(SMBHSTCMD), inb(SMBHSTADD), inb(SMBHSTDAT0), inb(SMBHSTDAT1)); return result; } /* * This is the main access entry for i2c-sch access * adap is i2c_adapter pointer, addr is the i2c device bus address, read_write * (0 for read and 1 for write), size is i2c transaction type and data is the * union of transaction for data to be transferred or data read from bus. * return 0 for success and others for failure. */ static s32 sch_access(struct i2c_adapter *adap, u16 addr, unsigned short flags, char read_write, u8 command, int size, union i2c_smbus_data *data) { int i, len, temp, rc; /* Make sure the SMBus host is not busy */ temp = inb(SMBHSTSTS) & 0x0f; if (temp & 0x08) { dev_dbg(&sch_adapter.dev, "SMBus busy (%02x)\n", temp); return -EAGAIN; } temp = inw(SMBHSTCLK); if (!temp) { /* * We can't determine if we have 33 or 25 MHz clock for * SMBus, so expect 33 MHz and calculate a bus clock of * 100 kHz. If we actually run at 25 MHz the bus will be * run ~75 kHz instead which should do no harm. */ dev_notice(&sch_adapter.dev, "Clock divider uninitialized. Setting defaults\n"); outw(backbone_speed / (4 * 100), SMBHSTCLK); } dev_dbg(&sch_adapter.dev, "access size: %d %s\n", size, (read_write)?"READ":"WRITE"); switch (size) { case I2C_SMBUS_QUICK: outb((addr << 1) | read_write, SMBHSTADD); size = SCH_QUICK; break; case I2C_SMBUS_BYTE: outb((addr << 1) | read_write, SMBHSTADD); if (read_write == I2C_SMBUS_WRITE) outb(command, SMBHSTCMD); size = SCH_BYTE; break; case I2C_SMBUS_BYTE_DATA: outb((addr << 1) | read_write, SMBHSTADD); outb(command, SMBHSTCMD); if (read_write == I2C_SMBUS_WRITE) outb(data->byte, SMBHSTDAT0); size = SCH_BYTE_DATA; break; case I2C_SMBUS_WORD_DATA: outb((addr << 1) | read_write, SMBHSTADD); outb(command, SMBHSTCMD); if (read_write == I2C_SMBUS_WRITE) { outb(data->word & 0xff, SMBHSTDAT0); outb((data->word & 0xff00) >> 8, SMBHSTDAT1); } size = SCH_WORD_DATA; break; case I2C_SMBUS_BLOCK_DATA: outb((addr << 1) | read_write, SMBHSTADD); outb(command, SMBHSTCMD); if (read_write == I2C_SMBUS_WRITE) { len = data->block[0]; if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) return -EINVAL; outb(len, SMBHSTDAT0); for (i = 1; i <= len; i++) outb(data->block[i], SMBBLKDAT+i-1); } size = SCH_BLOCK_DATA; break; default: dev_warn(&adap->dev, "Unsupported transaction %d\n", size); return -EOPNOTSUPP; } dev_dbg(&sch_adapter.dev, "write size %d to 0x%04x\n", size, SMBHSTCNT); outb((inb(SMBHSTCNT) & 0xb0) | (size & 0x7), SMBHSTCNT); rc = sch_transaction(); if (rc) /* Error in transaction */ return rc; if ((read_write == I2C_SMBUS_WRITE) || (size == SCH_QUICK)) return 0; switch (size) { case SCH_BYTE: case SCH_BYTE_DATA: data->byte = inb(SMBHSTDAT0); break; case SCH_WORD_DATA: data->word = inb(SMBHSTDAT0) + (inb(SMBHSTDAT1) << 8); break; case SCH_BLOCK_DATA: data->block[0] = inb(SMBHSTDAT0); if (data->block[0] == 0 || data->block[0] > I2C_SMBUS_BLOCK_MAX) return -EPROTO; for (i = 1; i <= data->block[0]; i++) data->block[i] = inb(SMBBLKDAT+i-1); break; } return 0; } static u32 sch_func(struct i2c_adapter *adapter) { return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_BLOCK_DATA; } static const struct i2c_algorithm smbus_algorithm = { .smbus_xfer = sch_access, .functionality = sch_func, }; static struct i2c_adapter sch_adapter = { .owner = THIS_MODULE, .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, .algo = &smbus_algorithm, }; static int smbus_sch_probe(struct platform_device *dev) { struct resource *res; int retval; res = platform_get_resource(dev, IORESOURCE_IO, 0); if (!res) return -EBUSY; if (!devm_request_region(&dev->dev, res->start, resource_size(res), dev->name)) { dev_err(&dev->dev, "SMBus region 0x%x already in use!\n", sch_smba); return -EBUSY; } sch_smba = res->start; dev_dbg(&dev->dev, "SMBA = 0x%X\n", sch_smba); /* set up the sysfs linkage to our parent device */ sch_adapter.dev.parent = &dev->dev; snprintf(sch_adapter.name, sizeof(sch_adapter.name), "SMBus SCH adapter at %04x", sch_smba); retval = i2c_add_adapter(&sch_adapter); if (retval) sch_smba = 0; return retval; } static void smbus_sch_remove(struct platform_device *pdev) { if (sch_smba) { i2c_del_adapter(&sch_adapter); sch_smba = 0; } } static struct platform_driver smbus_sch_driver = { .driver = { .name = "isch_smbus", }, .probe = smbus_sch_probe, .remove_new = smbus_sch_remove, }; module_platform_driver(smbus_sch_driver); MODULE_AUTHOR("Jacob Pan "); MODULE_DESCRIPTION("Intel SCH SMBus driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:isch_smbus");