diff options
Diffstat (limited to 'drivers/i2c/busses/i2c-emev2.c')
| -rw-r--r-- | drivers/i2c/busses/i2c-emev2.c | 332 |
1 files changed, 332 insertions, 0 deletions
diff --git a/drivers/i2c/busses/i2c-emev2.c b/drivers/i2c/busses/i2c-emev2.c new file mode 100644 index 000000000000..192ef6b50c79 --- /dev/null +++ b/drivers/i2c/busses/i2c-emev2.c @@ -0,0 +1,332 @@ +/* + * I2C driver for the Renesas EMEV2 SoC + * + * Copyright (C) 2015 Wolfram Sang <wsa@sang-engineering.com> + * Copyright 2013 Codethink Ltd. + * Copyright 2010-2015 Renesas Electronics Corporation + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 + * as published by the Free Software Foundation. + */ + +#include <linux/clk.h> +#include <linux/completion.h> +#include <linux/device.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/io.h> +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/sched.h> + +/* I2C Registers */ +#define I2C_OFS_IICACT0 0x00 /* start */ +#define I2C_OFS_IIC0 0x04 /* shift */ +#define I2C_OFS_IICC0 0x08 /* control */ +#define I2C_OFS_SVA0 0x0c /* slave address */ +#define I2C_OFS_IICCL0 0x10 /* clock select */ +#define I2C_OFS_IICX0 0x14 /* extension */ +#define I2C_OFS_IICS0 0x18 /* status */ +#define I2C_OFS_IICSE0 0x1c /* status For emulation */ +#define I2C_OFS_IICF0 0x20 /* IIC flag */ + +/* I2C IICACT0 Masks */ +#define I2C_BIT_IICE0 0x0001 + +/* I2C IICC0 Masks */ +#define I2C_BIT_LREL0 0x0040 +#define I2C_BIT_WREL0 0x0020 +#define I2C_BIT_SPIE0 0x0010 +#define I2C_BIT_WTIM0 0x0008 +#define I2C_BIT_ACKE0 0x0004 +#define I2C_BIT_STT0 0x0002 +#define I2C_BIT_SPT0 0x0001 + +/* I2C IICCL0 Masks */ +#define I2C_BIT_SMC0 0x0008 +#define I2C_BIT_DFC0 0x0004 + +/* I2C IICSE0 Masks */ +#define I2C_BIT_MSTS0 0x0080 +#define I2C_BIT_ALD0 0x0040 +#define I2C_BIT_EXC0 0x0020 +#define I2C_BIT_COI0 0x0010 +#define I2C_BIT_TRC0 0x0008 +#define I2C_BIT_ACKD0 0x0004 +#define I2C_BIT_STD0 0x0002 +#define I2C_BIT_SPD0 0x0001 + +/* I2C IICF0 Masks */ +#define I2C_BIT_STCF 0x0080 +#define I2C_BIT_IICBSY 0x0040 +#define I2C_BIT_STCEN 0x0002 +#define I2C_BIT_IICRSV 0x0001 + +struct em_i2c_device { + void __iomem *base; + struct i2c_adapter adap; + struct completion msg_done; + struct clk *sclk; +}; + +static inline void em_clear_set_bit(struct em_i2c_device *priv, u8 clear, u8 set, u8 reg) +{ + writeb((readb(priv->base + reg) & ~clear) | set, priv->base + reg); +} + +static int em_i2c_wait_for_event(struct em_i2c_device *priv) +{ + unsigned long time_left; + int status; + + reinit_completion(&priv->msg_done); + + time_left = wait_for_completion_timeout(&priv->msg_done, priv->adap.timeout); + + if (!time_left) + return -ETIMEDOUT; + + status = readb(priv->base + I2C_OFS_IICSE0); + return status & I2C_BIT_ALD0 ? -EAGAIN : status; +} + +static void em_i2c_stop(struct em_i2c_device *priv) +{ + /* Send Stop condition */ + em_clear_set_bit(priv, 0, I2C_BIT_SPT0 | I2C_BIT_SPIE0, I2C_OFS_IICC0); + + /* Wait for stop condition */ + em_i2c_wait_for_event(priv); +} + +static void em_i2c_reset(struct i2c_adapter *adap) +{ + struct em_i2c_device *priv = i2c_get_adapdata(adap); + int retr; + + /* If I2C active */ + if (readb(priv->base + I2C_OFS_IICACT0) & I2C_BIT_IICE0) { + /* Disable I2C operation */ + writeb(0, priv->base + I2C_OFS_IICACT0); + + retr = 1000; + while (readb(priv->base + I2C_OFS_IICACT0) == 1 && retr) + retr--; + WARN_ON(retr == 0); + } + + /* Transfer mode set */ + writeb(I2C_BIT_DFC0, priv->base + I2C_OFS_IICCL0); + + /* Can Issue start without detecting a stop, Reservation disabled. */ + writeb(I2C_BIT_STCEN | I2C_BIT_IICRSV, priv->base + I2C_OFS_IICF0); + + /* I2C enable, 9 bit interrupt mode */ + writeb(I2C_BIT_WTIM0, priv->base + I2C_OFS_IICC0); + + /* Enable I2C operation */ + writeb(I2C_BIT_IICE0, priv->base + I2C_OFS_IICACT0); + + retr = 1000; + while (readb(priv->base + I2C_OFS_IICACT0) == 0 && retr) + retr--; + WARN_ON(retr == 0); +} + +static int __em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, + int stop) +{ + struct em_i2c_device *priv = i2c_get_adapdata(adap); + int count, status, read = !!(msg->flags & I2C_M_RD); + + /* Send start condition */ + em_clear_set_bit(priv, 0, I2C_BIT_ACKE0 | I2C_BIT_WTIM0, I2C_OFS_IICC0); + em_clear_set_bit(priv, 0, I2C_BIT_STT0, I2C_OFS_IICC0); + + /* Send slave address and R/W type */ + writeb((msg->addr << 1) | read, priv->base + I2C_OFS_IIC0); + + /* Wait for transaction */ + status = em_i2c_wait_for_event(priv); + if (status < 0) + goto out_reset; + + /* Received NACK (result of setting slave address and R/W) */ + if (!(status & I2C_BIT_ACKD0)) { + em_i2c_stop(priv); + goto out; + } + + /* Extra setup for read transactions */ + if (read) { + /* 8 bit interrupt mode */ + em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_ACKE0, I2C_OFS_IICC0); + em_clear_set_bit(priv, I2C_BIT_WTIM0, I2C_BIT_WREL0, I2C_OFS_IICC0); + + /* Wait for transaction */ + status = em_i2c_wait_for_event(priv); + if (status < 0) + goto out_reset; + } + + /* Send / receive data */ + for (count = 0; count < msg->len; count++) { + if (read) { /* Read transaction */ + msg->buf[count] = readb(priv->base + I2C_OFS_IIC0); + em_clear_set_bit(priv, 0, I2C_BIT_WREL0, I2C_OFS_IICC0); + + } else { /* Write transaction */ + /* Received NACK */ + if (!(status & I2C_BIT_ACKD0)) { + em_i2c_stop(priv); + goto out; + } + + /* Write data */ + writeb(msg->buf[count], priv->base + I2C_OFS_IIC0); + } + + /* Wait for R/W transaction */ + status = em_i2c_wait_for_event(priv); + if (status < 0) + goto out_reset; + } + + if (stop) + em_i2c_stop(priv); + + return count; + +out_reset: + em_i2c_reset(adap); +out: + return status < 0 ? status : -ENXIO; +} + +static int em_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, + int num) +{ + struct em_i2c_device *priv = i2c_get_adapdata(adap); + int ret, i; + + if (readb(priv->base + I2C_OFS_IICF0) & I2C_BIT_IICBSY) + return -EAGAIN; + + for (i = 0; i < num; i++) { + ret = __em_i2c_xfer(adap, &msgs[i], (i == (num - 1))); + if (ret < 0) + return ret; + } + + /* I2C transfer completed */ + return num; +} + +static irqreturn_t em_i2c_irq_handler(int this_irq, void *dev_id) +{ + struct em_i2c_device *priv = dev_id; + + complete(&priv->msg_done); + return IRQ_HANDLED; +} + +static u32 em_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +static struct i2c_algorithm em_i2c_algo = { + .master_xfer = em_i2c_xfer, + .functionality = em_i2c_func, +}; + +static int em_i2c_probe(struct platform_device *pdev) +{ + struct em_i2c_device *priv; + struct resource *r; + int irq, ret; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + priv->base = devm_ioremap_resource(&pdev->dev, r); + if (IS_ERR(priv->base)) + return PTR_ERR(priv->base); + + strlcpy(priv->adap.name, "EMEV2 I2C", sizeof(priv->adap.name)); + + priv->sclk = devm_clk_get(&pdev->dev, "sclk"); + if (IS_ERR(priv->sclk)) + return PTR_ERR(priv->sclk); + + clk_prepare_enable(priv->sclk); + + priv->adap.timeout = msecs_to_jiffies(100); + priv->adap.retries = 5; + priv->adap.dev.parent = &pdev->dev; + priv->adap.algo = &em_i2c_algo; + priv->adap.owner = THIS_MODULE; + priv->adap.dev.of_node = pdev->dev.of_node; + + init_completion(&priv->msg_done); + + platform_set_drvdata(pdev, priv); + i2c_set_adapdata(&priv->adap, priv); + + em_i2c_reset(&priv->adap); + + irq = platform_get_irq(pdev, 0); + ret = devm_request_irq(&pdev->dev, irq, em_i2c_irq_handler, 0, + "em_i2c", priv); + if (ret) + goto err_clk; + + ret = i2c_add_adapter(&priv->adap); + + if (ret) + goto err_clk; + + dev_info(&pdev->dev, "Added i2c controller %d, irq %d\n", priv->adap.nr, irq); + + return 0; + +err_clk: + clk_disable_unprepare(priv->sclk); + return ret; +} + +static int em_i2c_remove(struct platform_device *dev) +{ + struct em_i2c_device *priv = platform_get_drvdata(dev); + + i2c_del_adapter(&priv->adap); + clk_disable_unprepare(priv->sclk); + + return 0; +} + +static const struct of_device_id em_i2c_ids[] = { + { .compatible = "renesas,iic-emev2", }, + { } +}; + +static struct platform_driver em_i2c_driver = { + .probe = em_i2c_probe, + .remove = em_i2c_remove, + .driver = { + .name = "em-i2c", + .of_match_table = em_i2c_ids, + } +}; +module_platform_driver(em_i2c_driver); + +MODULE_DESCRIPTION("EMEV2 I2C bus driver"); +MODULE_AUTHOR("Ian Molton and Wolfram Sang <wsa@sang-engineering.com>"); +MODULE_LICENSE("GPL v2"); +MODULE_DEVICE_TABLE(of, em_i2c_ids); |