diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-wmt.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-wmt.c | 479 |
1 files changed, 479 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-wmt.c b/drivers/i2c/busses/i2c-wmt.c new file mode 100644 index 00000000000..baaa7d15b73 --- /dev/null +++ b/drivers/i2c/busses/i2c-wmt.c @@ -0,0 +1,479 @@ +/* + * Wondermedia I2C Master Mode Driver + * + * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz> + * + * Derived from GPLv2+ licensed source: + * - Copyright (C) 2008 WonderMedia Technologies, Inc. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2, or + * (at your option) any later version. as published by the Free Software + * Foundation + */ + +#include <linux/clk.h> +#include <linux/delay.h> +#include <linux/err.h> +#include <linux/i2c.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/module.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/of_i2c.h> +#include <linux/of_irq.h> +#include <linux/platform_device.h> + +#define REG_CR 0x00 +#define REG_TCR 0x02 +#define REG_CSR 0x04 +#define REG_ISR 0x06 +#define REG_IMR 0x08 +#define REG_CDR 0x0A +#define REG_TR 0x0C +#define REG_MCR 0x0E +#define REG_SLAVE_CR 0x10 +#define REG_SLAVE_SR 0x12 +#define REG_SLAVE_ISR 0x14 +#define REG_SLAVE_IMR 0x16 +#define REG_SLAVE_DR 0x18 +#define REG_SLAVE_TR 0x1A + +/* REG_CR Bit fields */ +#define CR_TX_NEXT_ACK 0x0000 +#define CR_ENABLE 0x0001 +#define CR_TX_NEXT_NO_ACK 0x0002 +#define CR_TX_END 0x0004 +#define CR_CPU_RDY 0x0008 +#define SLAV_MODE_SEL 0x8000 + +/* REG_TCR Bit fields */ +#define TCR_STANDARD_MODE 0x0000 +#define TCR_MASTER_WRITE 0x0000 +#define TCR_HS_MODE 0x2000 +#define TCR_MASTER_READ 0x4000 +#define TCR_FAST_MODE 0x8000 +#define TCR_SLAVE_ADDR_MASK 0x007F + +/* REG_ISR Bit fields */ +#define ISR_NACK_ADDR 0x0001 +#define ISR_BYTE_END 0x0002 +#define ISR_SCL_TIMEOUT 0x0004 +#define ISR_WRITE_ALL 0x0007 + +/* REG_IMR Bit fields */ +#define IMR_ENABLE_ALL 0x0007 + +/* REG_CSR Bit fields */ +#define CSR_RCV_NOT_ACK 0x0001 +#define CSR_RCV_ACK_MASK 0x0001 +#define CSR_READY_MASK 0x0002 + +/* REG_TR */ +#define SCL_TIMEOUT(x) (((x) & 0xFF) << 8) +#define TR_STD 0x0064 +#define TR_HS 0x0019 + +/* REG_MCR */ +#define MCR_APB_96M 7 +#define MCR_APB_166M 12 + +#define I2C_MODE_STANDARD 0 +#define I2C_MODE_FAST 1 + +#define WMT_I2C_TIMEOUT (msecs_to_jiffies(1000)) + +struct wmt_i2c_dev { + struct i2c_adapter adapter; + struct completion complete; + struct device *dev; + void __iomem *base; + struct clk *clk; + int mode; + int irq; + u16 cmd_status; +}; + +static int wmt_i2c_wait_bus_not_busy(struct wmt_i2c_dev *i2c_dev) +{ + unsigned long timeout; + + timeout = jiffies + WMT_I2C_TIMEOUT; + while (!(readw(i2c_dev->base + REG_CSR) & CSR_READY_MASK)) { + if (time_after(jiffies, timeout)) { + dev_warn(i2c_dev->dev, "timeout waiting for bus ready\n"); + return -EBUSY; + } + msleep(20); + } + + return 0; +} + +static int wmt_check_status(struct wmt_i2c_dev *i2c_dev) +{ + int ret = 0; + + if (i2c_dev->cmd_status & ISR_NACK_ADDR) + ret = -EIO; + + if (i2c_dev->cmd_status & ISR_SCL_TIMEOUT) + ret = -ETIMEDOUT; + + return ret; +} + +static int wmt_i2c_write(struct i2c_adapter *adap, struct i2c_msg *pmsg, + int last) +{ + struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + u16 val, tcr_val; + int ret, wait_result; + int xfer_len = 0; + + if (!(pmsg->flags & I2C_M_NOSTART)) { + ret = wmt_i2c_wait_bus_not_busy(i2c_dev); + if (ret < 0) + return ret; + } + + if (pmsg->len == 0) { + /* + * We still need to run through the while (..) once, so + * start at -1 and break out early from the loop + */ + xfer_len = -1; + writew(0, i2c_dev->base + REG_CDR); + } else { + writew(pmsg->buf[0] & 0xFF, i2c_dev->base + REG_CDR); + } + + if (!(pmsg->flags & I2C_M_NOSTART)) { + val = readw(i2c_dev->base + REG_CR); + val &= ~CR_TX_END; + writew(val, i2c_dev->base + REG_CR); + + val = readw(i2c_dev->base + REG_CR); + val |= CR_CPU_RDY; + writew(val, i2c_dev->base + REG_CR); + } + + INIT_COMPLETION(i2c_dev->complete); + + if (i2c_dev->mode == I2C_MODE_STANDARD) + tcr_val = TCR_STANDARD_MODE; + else + tcr_val = TCR_FAST_MODE; + + tcr_val |= (TCR_MASTER_WRITE | (pmsg->addr & TCR_SLAVE_ADDR_MASK)); + + writew(tcr_val, i2c_dev->base + REG_TCR); + + if (pmsg->flags & I2C_M_NOSTART) { + val = readw(i2c_dev->base + REG_CR); + val |= CR_CPU_RDY; + writew(val, i2c_dev->base + REG_CR); + } + + while (xfer_len < pmsg->len) { + wait_result = wait_for_completion_timeout(&i2c_dev->complete, + 500 * HZ / 1000); + + if (wait_result == 0) + return -ETIMEDOUT; + + ret = wmt_check_status(i2c_dev); + if (ret) + return ret; + + xfer_len++; + + val = readw(i2c_dev->base + REG_CSR); + if ((val & CSR_RCV_ACK_MASK) == CSR_RCV_NOT_ACK) { + dev_dbg(i2c_dev->dev, "write RCV NACK error\n"); + return -EIO; + } + + if (pmsg->len == 0) { + val = CR_TX_END | CR_CPU_RDY | CR_ENABLE; + writew(val, i2c_dev->base + REG_CR); + break; + } + + if (xfer_len == pmsg->len) { + if (last != 1) + writew(CR_ENABLE, i2c_dev->base + REG_CR); + } else { + writew(pmsg->buf[xfer_len] & 0xFF, i2c_dev->base + + REG_CDR); + writew(CR_CPU_RDY | CR_ENABLE, i2c_dev->base + REG_CR); + } + } + + return 0; +} + +static int wmt_i2c_read(struct i2c_adapter *adap, struct i2c_msg *pmsg, + int last) +{ + struct wmt_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + u16 val, tcr_val; + int ret, wait_result; + u32 xfer_len = 0; + + if (!(pmsg->flags & I2C_M_NOSTART)) { + ret = wmt_i2c_wait_bus_not_busy(i2c_dev); + if (ret < 0) + return ret; + } + + val = readw(i2c_dev->base + REG_CR); + val &= ~CR_TX_END; + writew(val, i2c_dev->base + REG_CR); + + val = readw(i2c_dev->base + REG_CR); + val &= ~CR_TX_NEXT_NO_ACK; + writew(val, i2c_dev->base + REG_CR); + + if (!(pmsg->flags & I2C_M_NOSTART)) { + val = readw(i2c_dev->base + REG_CR); + val |= CR_CPU_RDY; + writew(val, i2c_dev->base + REG_CR); + } + + if (pmsg->len == 1) { + val = readw(i2c_dev->base + REG_CR); + val |= CR_TX_NEXT_NO_ACK; + writew(val, i2c_dev->base + REG_CR); + } + + INIT_COMPLETION(i2c_dev->complete); + + if (i2c_dev->mode == I2C_MODE_STANDARD) + tcr_val = TCR_STANDARD_MODE; + else + tcr_val = TCR_FAST_MODE; + + tcr_val |= TCR_MASTER_READ | (pmsg->addr & TCR_SLAVE_ADDR_MASK); + + writew(tcr_val, i2c_dev->base + REG_TCR); + + if (pmsg->flags & I2C_M_NOSTART) { + val = readw(i2c_dev->base + REG_CR); + val |= CR_CPU_RDY; + writew(val, i2c_dev->base + REG_CR); + } + + while (xfer_len < pmsg->len) { + wait_result = wait_for_completion_timeout(&i2c_dev->complete, + 500 * HZ / 1000); + + if (!wait_result) + return -ETIMEDOUT; + + ret = wmt_check_status(i2c_dev); + if (ret) + return ret; + + pmsg->buf[xfer_len] = readw(i2c_dev->base + REG_CDR) >> 8; + xfer_len++; + + if (xfer_len == pmsg->len - 1) { + val = readw(i2c_dev->base + REG_CR); + val |= (CR_TX_NEXT_NO_ACK | CR_CPU_RDY); + writew(val, i2c_dev->base + REG_CR); + } else { + val = readw(i2c_dev->base + REG_CR); + val |= CR_CPU_RDY; + writew(val, i2c_dev->base + REG_CR); + } + } + + return 0; +} + +static int wmt_i2c_xfer(struct i2c_adapter *adap, + struct i2c_msg msgs[], + int num) +{ + struct i2c_msg *pmsg; + int i, is_last; + int ret = 0; + + for (i = 0; ret >= 0 && i < num; i++) { + is_last = ((i + 1) == num); + + pmsg = &msgs[i]; + if (pmsg->flags & I2C_M_RD) + ret = wmt_i2c_read(adap, pmsg, is_last); + else + ret = wmt_i2c_write(adap, pmsg, is_last); + } + + return (ret < 0) ? ret : i; +} + +static u32 wmt_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_NOSTART; +} + +static const struct i2c_algorithm wmt_i2c_algo = { + .master_xfer = wmt_i2c_xfer, + .functionality = wmt_i2c_func, +}; + +static irqreturn_t wmt_i2c_isr(int irq, void *data) +{ + struct wmt_i2c_dev *i2c_dev = data; + + /* save the status and write-clear it */ + i2c_dev->cmd_status = readw(i2c_dev->base + REG_ISR); + writew(i2c_dev->cmd_status, i2c_dev->base + REG_ISR); + + complete(&i2c_dev->complete); + + return IRQ_HANDLED; +} + +static int wmt_i2c_reset_hardware(struct wmt_i2c_dev *i2c_dev) +{ + int err; + + err = clk_prepare_enable(i2c_dev->clk); + if (err) { + dev_err(i2c_dev->dev, "failed to enable clock\n"); + return err; + } + + err = clk_set_rate(i2c_dev->clk, 20000000); + if (err) { + dev_err(i2c_dev->dev, "failed to set clock = 20Mhz\n"); + return err; + } + + writew(0, i2c_dev->base + REG_CR); + writew(MCR_APB_166M, i2c_dev->base + REG_MCR); + writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR); + writew(IMR_ENABLE_ALL, i2c_dev->base + REG_IMR); + writew(CR_ENABLE, i2c_dev->base + REG_CR); + readw(i2c_dev->base + REG_CSR); /* read clear */ + writew(ISR_WRITE_ALL, i2c_dev->base + REG_ISR); + + if (i2c_dev->mode == I2C_MODE_STANDARD) + writew(SCL_TIMEOUT(128) | TR_STD, i2c_dev->base + REG_TR); + else + writew(SCL_TIMEOUT(128) | TR_HS, i2c_dev->base + REG_TR); + + return 0; +} + +static int wmt_i2c_probe(struct platform_device *pdev) +{ + struct device_node *np = pdev->dev.of_node; + struct wmt_i2c_dev *i2c_dev; + struct i2c_adapter *adap; + struct resource *res; + int err; + u32 clk_rate; + + i2c_dev = devm_kzalloc(&pdev->dev, sizeof(*i2c_dev), GFP_KERNEL); + if (!i2c_dev) { + dev_err(&pdev->dev, "device memory allocation failed\n"); + return -ENOMEM; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + i2c_dev->base = devm_ioremap_resource(&pdev->dev, res); + if (IS_ERR(i2c_dev->base)) + return PTR_ERR(i2c_dev->base); + + i2c_dev->irq = irq_of_parse_and_map(np, 0); + if (!i2c_dev->irq) { + dev_err(&pdev->dev, "irq missing or invalid\n"); + return -EINVAL; + } + + i2c_dev->clk = of_clk_get(np, 0); + if (IS_ERR(i2c_dev->clk)) { + dev_err(&pdev->dev, "unable to request clock\n"); + return PTR_ERR(i2c_dev->clk); + } + + i2c_dev->mode = I2C_MODE_STANDARD; + err = of_property_read_u32(np, "clock-frequency", &clk_rate); + if ((!err) && (clk_rate == 400000)) + i2c_dev->mode = I2C_MODE_FAST; + + i2c_dev->dev = &pdev->dev; + + err = devm_request_irq(&pdev->dev, i2c_dev->irq, wmt_i2c_isr, 0, + "i2c", i2c_dev); + if (err) { + dev_err(&pdev->dev, "failed to request irq %i\n", i2c_dev->irq); + return err; + } + + adap = &i2c_dev->adapter; + i2c_set_adapdata(adap, i2c_dev); + strlcpy(adap->name, "WMT I2C adapter", sizeof(adap->name)); + adap->owner = THIS_MODULE; + adap->algo = &wmt_i2c_algo; + adap->dev.parent = &pdev->dev; + adap->dev.of_node = pdev->dev.of_node; + + init_completion(&i2c_dev->complete); + + err = wmt_i2c_reset_hardware(i2c_dev); + if (err) { + dev_err(&pdev->dev, "error initializing hardware\n"); + return err; + } + + err = i2c_add_adapter(adap); + if (err) { + dev_err(&pdev->dev, "failed to add adapter\n"); + return err; + } + + platform_set_drvdata(pdev, i2c_dev); + + of_i2c_register_devices(adap); + + return 0; +} + +static int wmt_i2c_remove(struct platform_device *pdev) +{ + struct wmt_i2c_dev *i2c_dev = platform_get_drvdata(pdev); + + /* Disable interrupts, clock and delete adapter */ + writew(0, i2c_dev->base + REG_IMR); + clk_disable_unprepare(i2c_dev->clk); + i2c_del_adapter(&i2c_dev->adapter); + + return 0; +} + +static struct of_device_id wmt_i2c_dt_ids[] = { + { .compatible = "wm,wm8505-i2c" }, + { /* Sentinel */ }, +}; + +static struct platform_driver wmt_i2c_driver = { + .probe = wmt_i2c_probe, + .remove = wmt_i2c_remove, + .driver = { + .name = "wmt-i2c", + .owner = THIS_MODULE, + .of_match_table = wmt_i2c_dt_ids, + }, +}; + +module_platform_driver(wmt_i2c_driver); + +MODULE_DESCRIPTION("Wondermedia I2C master-mode bus adapter"); +MODULE_AUTHOR("Tony Prisk <linux@prisktech.co.nz>"); +MODULE_LICENSE("GPL"); +MODULE_DEVICE_TABLE(of, wmt_i2c_dt_ids); |