diff options
Diffstat (limited to 'drivers/i2c/busses/mxc_i2c.c')
| -rw-r--r-- | drivers/i2c/busses/mxc_i2c.c | 808 |
1 files changed, 808 insertions, 0 deletions
diff --git a/drivers/i2c/busses/mxc_i2c.c b/drivers/i2c/busses/mxc_i2c.c new file mode 100644 index 000000000000..b47f9db4b476 --- /dev/null +++ b/drivers/i2c/busses/mxc_i2c.c @@ -0,0 +1,808 @@ +/* + * Copyright (C) 2004-2010 Freescale Semiconductor, Inc. All Rights Reserved. + */ + +/* + * The code contained herein is licensed under the GNU General Public + * License. You may obtain a copy of the GNU General Public License + * Version 2 or later at the following locations: + * + * http://www.opensource.org/licenses/gpl-license.html + * http://www.gnu.org/copyleft/gpl.html + */ + +/*! + * @file mxc_i2c.c + * + * @brief Driver for the Freescale Semiconductor MXC I2C buses. + * + * Based on i2c driver algorithm for PCF8584 adapters + * + * @ingroup MXCI2C + */ + +/* + * Include Files + */ +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/device.h> +#include <linux/delay.h> +#include <linux/interrupt.h> +#include <linux/platform_device.h> +#include <linux/i2c.h> +#include <linux/io.h> +#include <linux/fsl_devices.h> +#include <linux/clk.h> +#include <linux/slab.h> +#include <asm/irq.h> +#include "mxc_i2c_reg.h" + +/*! + * In case the MXC device has multiple I2C modules, this structure is used to + * store information specific to each I2C module. + */ +typedef struct { + /*! + * This structure is used to identify the physical i2c bus along with + * the access algorithms necessary to access it. + */ + struct i2c_adapter adap; + + /*! + * This waitqueue is used to wait for the data transfer to complete. + */ + wait_queue_head_t wq; + + /*! + * The base address of the I2C device. + */ + void __iomem *membase; + + /*! + * The interrupt number used by the I2C device. + */ + int irq; + + /*! + * The default clock divider value to be used. + */ + unsigned int clkdiv; + + /*! + * The clock source for the device. + */ + struct clk *clk; + + /*! + * The current power state of the device + */ + bool low_power; + + /*! + * Boolean to indicate if data was transferred + */ + bool transfer_done; + + /*! + * Boolean to indicate if we received an ACK for the data transmitted + */ + bool tx_success; +} mxc_i2c_device; + +struct clk_div_table { + int reg_value; + int div; +}; + +static const struct clk_div_table i2c_clk_table[] = { + {0x20, 22}, {0x21, 24}, {0x22, 26}, {0x23, 28}, + {0, 30}, {1, 32}, {0x24, 32}, {2, 36}, + {0x25, 36}, {0x26, 40}, {3, 42}, {0x27, 44}, + {4, 48}, {0x28, 48}, {5, 52}, {0x29, 56}, + {6, 60}, {0x2A, 64}, {7, 72}, {0x2B, 72}, + {8, 80}, {0x2C, 80}, {9, 88}, {0x2D, 96}, + {0xA, 104}, {0x2E, 112}, {0xB, 128}, {0x2F, 128}, + {0xC, 144}, {0xD, 160}, {0x30, 160}, {0xE, 192}, + {0x31, 192}, {0x32, 224}, {0xF, 240}, {0x33, 256}, + {0x10, 288}, {0x11, 320}, {0x34, 320}, {0x12, 384}, + {0x35, 384}, {0x36, 448}, {0x13, 480}, {0x37, 512}, + {0x14, 576}, {0x15, 640}, {0x38, 640}, {0x16, 768}, + {0x39, 768}, {0x3A, 896}, {0x17, 960}, {0x3B, 1024}, + {0x18, 1152}, {0x19, 1280}, {0x3C, 1280}, {0x1A, 1536}, + {0x3D, 1536}, {0x3E, 1792}, {0x1B, 1920}, {0x3F, 2048}, + {0x1C, 2304}, {0x1D, 2560}, {0x1E, 3072}, {0x1F, 3840}, + {0, 0} +}; + +extern void gpio_i2c_active(int i2c_num); +extern void gpio_i2c_inactive(int i2c_num); + +/*! + * Transmit a \b STOP signal to the slave device. + * + * @param dev the mxc i2c structure used to get to the right i2c device + */ +static void mxc_i2c_stop(mxc_i2c_device *dev) +{ + unsigned int cr, sr; + int retry = 16; + + cr = readw(dev->membase + MXC_I2CR); + cr &= ~(MXC_I2CR_MSTA | MXC_I2CR_MTX); + writew(cr, dev->membase + MXC_I2CR); + + /* Wait till the Bus Busy bit is reset */ + sr = readw(dev->membase + MXC_I2SR); + while (retry-- && ((sr & MXC_I2SR_IBB))) { + udelay(3); + sr = readw(dev->membase + MXC_I2SR); + } + if (retry <= 0) + dev_err(&dev->adap.dev, "Could not set I2C Bus Busy bit" + " to zero.\n"); +} + +/*! + * Wait for the transmission of the data byte to complete. This function waits + * till we get a signal from the interrupt service routine indicating completion + * of the address cycle or we time out. + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param trans_flag transfer flag + * + * + * @return The function returns 0 on success or -1 if an ack was not received + */ + +static int mxc_i2c_wait_for_tc(mxc_i2c_device *dev, int trans_flag) +{ + int retry = 16; + + while (retry-- && !dev->transfer_done) { + wait_event_interruptible_timeout(dev->wq, + dev->transfer_done, + dev->adap.timeout); + } + dev->transfer_done = false; + + if (retry <= 0) { + /* Unable to send data */ + dev_err(&dev->adap.dev, "Data not transmitted\n"); + return -1; + } + + if (!dev->tx_success) { + /* An ACK was not received for transmitted byte */ + dev_err(&dev->adap.dev, "ACK not received \n"); + return -1; + } + + return 0; +} + +/*! + * Transmit a \b START signal to the slave device. + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param *msg pointer to a message structure that contains the slave + * address + * + * @return The function returns EBUSY on failure, 0 on success. + */ +static int mxc_i2c_start(mxc_i2c_device *dev, struct i2c_msg *msg) +{ + volatile unsigned int cr, sr; + unsigned int addr_trans; + int retry = 16; + + /* + * Set the slave address and the requested transfer mode + * in the data register + */ + addr_trans = msg->addr << 1; + if (msg->flags & I2C_M_RD) { + addr_trans |= 0x01; + } + + /* Set the Master bit */ + cr = readw(dev->membase + MXC_I2CR); + cr |= MXC_I2CR_MSTA; + writew(cr, dev->membase + MXC_I2CR); + + /* Wait till the Bus Busy bit is set */ + sr = readw(dev->membase + MXC_I2SR); + while (retry-- && (!(sr & MXC_I2SR_IBB))) { + udelay(3); + sr = readw(dev->membase + MXC_I2SR); + } + if (retry <= 0) { + dev_err(&dev->adap.dev, "Could not grab Bus ownership\n"); + return -EBUSY; + } + + /* Set the Transmit bit */ + cr = readw(dev->membase + MXC_I2CR); + cr |= MXC_I2CR_MTX; + writew(cr, dev->membase + MXC_I2CR); + + writew(addr_trans, dev->membase + MXC_I2DR); + return 0; +} + +/*! + * Transmit a \b REPEAT START to the slave device + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param *msg pointer to a message structure that contains the slave + * address + */ +static int mxc_i2c_repstart(mxc_i2c_device *dev, struct i2c_msg *msg) +{ + volatile unsigned int cr, sr; + unsigned int addr_trans; + int retry = 16; + + /* + * Set the slave address and the requested transfer mode + * in the data register + */ + addr_trans = msg->addr << 1; + if (msg->flags & I2C_M_RD) { + addr_trans |= 0x01; + } + cr = readw(dev->membase + MXC_I2CR); + cr |= MXC_I2CR_RSTA; + writew(cr, dev->membase + MXC_I2CR); + /* Wait till the Bus Busy bit is set */ + sr = readw(dev->membase + MXC_I2SR); + while (retry-- && (!(sr & MXC_I2SR_IBB))) { + udelay(3); + sr = readw(dev->membase + MXC_I2SR); + } + if (retry <= 0) { + dev_err(&dev->adap.dev, "Could not grab Bus ownership\n"); + return -EBUSY; + } + writew(addr_trans, dev->membase + MXC_I2DR); + return 0; +} + +/*! + * Read the received data. The function waits till data is available or times + * out. Generates a stop signal if this is the last message to be received. + * Sends an ack for all the bytes received except the last byte. + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param *msg pointer to a message structure that contains the slave + * address and a pointer to the receive buffer + * @param last indicates that this is the last message to be received + * @param addr_comp flag indicates that we just finished the address cycle + * + * @return The function returns the number of bytes read or -1 on time out. + */ +static int mxc_i2c_readbytes(mxc_i2c_device *dev, struct i2c_msg *msg, + int last, int addr_comp) +{ + int i; + char *buf = msg->buf; + int len = msg->len; + volatile unsigned int cr; + + cr = readw(dev->membase + MXC_I2CR); + /* + * Clear MTX to switch to receive mode. + */ + cr &= ~MXC_I2CR_MTX; + /* + * Clear the TXAK bit to gen an ack when receiving only one byte. + */ + if (len == 1) { + cr |= MXC_I2CR_TXAK; + } else { + cr &= ~MXC_I2CR_TXAK; + } + writew(cr, dev->membase + MXC_I2CR); + /* + * Dummy read only at the end of an address cycle + */ + if (addr_comp > 0) { + readw(dev->membase + MXC_I2DR); + } + + for (i = 0; i < len; i++) { + /* + * Wait for data transmission to complete + */ + if (mxc_i2c_wait_for_tc(dev, msg->flags)) { + mxc_i2c_stop(dev); + return -1; + } + /* + * Do not generate an ACK for the last byte + */ + if (i == (len - 2)) { + cr = readw(dev->membase + MXC_I2CR); + cr |= MXC_I2CR_TXAK; + writew(cr, dev->membase + MXC_I2CR); + } else if (i == (len - 1)) { + if (last) { + mxc_i2c_stop(dev); + } + } + /* Read the data */ + *buf++ = readw(dev->membase + MXC_I2DR); + } + + return i; +} + +/*! + * Write the data to the data register. Generates a stop signal if this is + * the last message to be sent or if no ack was received for the data sent. + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param *msg pointer to a message structure that contains the slave + * address and data to be sent + * @param last indicates that this is the last message to be received + * + * @return The function returns the number of bytes written or -1 on time out + * or if no ack was received for the data that was sent. + */ +static int mxc_i2c_writebytes(mxc_i2c_device *dev, struct i2c_msg *msg, + int last) +{ + int i; + char *buf = msg->buf; + int len = msg->len; + volatile unsigned int cr; + + cr = readw(dev->membase + MXC_I2CR); + /* Set MTX to switch to transmit mode */ + cr |= MXC_I2CR_MTX; + writew(cr, dev->membase + MXC_I2CR); + + for (i = 0; i < len; i++) { + /* + * Write the data + */ + writew(*buf++, dev->membase + MXC_I2DR); + if (mxc_i2c_wait_for_tc(dev, msg->flags)) { + mxc_i2c_stop(dev); + return -1; + } + } + if (last > 0) { + mxc_i2c_stop(dev); + } + + return i; +} + +/*! + * Function enables the I2C module and initializes the registers. + * + * @param dev the mxc i2c structure used to get to the right i2c device + * @param trans_flag transfer flag + */ +static void mxc_i2c_module_en(mxc_i2c_device *dev, int trans_flag) +{ + clk_enable(dev->clk); + /* Set the frequency divider */ + writew(dev->clkdiv, dev->membase + MXC_IFDR); + /* Clear the status register */ + writew(0x0, dev->membase + MXC_I2SR); + /* Enable I2C and its interrupts */ + writew(MXC_I2CR_IEN, dev->membase + MXC_I2CR); + writew(MXC_I2CR_IEN | MXC_I2CR_IIEN, dev->membase + MXC_I2CR); +} + +/*! + * Disables the I2C module. + * + * @param dev the mxc i2c structure used to get to the right i2c device + */ +static void mxc_i2c_module_dis(mxc_i2c_device *dev) +{ + writew(0x0, dev->membase + MXC_I2CR); + clk_disable(dev->clk); +} + +/*! + * The function is registered in the adapter structure. It is called when an MXC + * driver wishes to transfer data to a device connected to the I2C device. + * + * @param adap adapter structure for the MXC i2c device + * @param msgs[] array of messages to be transferred to the device + * @param num number of messages to be transferred to the device + * + * @return The function returns the number of messages transferred, + * \b -EREMOTEIO on I2C failure and a 0 if the num argument is + * less than 0. + */ +static int mxc_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], + int num) +{ + mxc_i2c_device *dev = (mxc_i2c_device *) (i2c_get_adapdata(adap)); + int i, ret = 0, addr_comp = 0; + volatile unsigned int sr; + int retry = 5; + + if (dev->low_power) { + dev_err(&dev->adap.dev, "I2C Device in low power mode\n"); + return -EREMOTEIO; + } + + if (num < 1) { + return 0; + } + + mxc_i2c_module_en(dev, msgs[0].flags); + sr = readw(dev->membase + MXC_I2SR); + /* + * Check bus state + */ + + while ((sr & MXC_I2SR_IBB) && retry--) { + udelay(5); + sr = readw(dev->membase + MXC_I2SR); + } + + if ((sr & MXC_I2SR_IBB) && retry < 0) { + mxc_i2c_module_dis(dev); + dev_err(&dev->adap.dev, "Bus busy\n"); + return -EREMOTEIO; + } + + dev->transfer_done = false; + dev->tx_success = false; + for (i = 0; i < num && ret >= 0; i++) { + addr_comp = 0; + /* + * Send the slave address and transfer direction in the + * address cycle + */ + if (i == 0) { + /* + * Send a start or repeat start signal + */ + if (mxc_i2c_start(dev, &msgs[0])) + return -EREMOTEIO; + /* Wait for the address cycle to complete */ + if (mxc_i2c_wait_for_tc(dev, msgs[0].flags)) { + mxc_i2c_stop(dev); + mxc_i2c_module_dis(dev); + return -EREMOTEIO; + } + addr_comp = 1; + } else { + /* + * Generate repeat start only if required i.e the address + * changed or the transfer direction changed + */ + if ((msgs[i].addr != msgs[i - 1].addr) || + ((msgs[i].flags & I2C_M_RD) != + (msgs[i - 1].flags & I2C_M_RD))) { + mxc_i2c_repstart(dev, &msgs[i]); + /* Wait for the address cycle to complete */ + if (mxc_i2c_wait_for_tc(dev, msgs[i].flags)) { + mxc_i2c_stop(dev); + mxc_i2c_module_dis(dev); + return -EREMOTEIO; + } + addr_comp = 1; + } + } + + /* Transfer the data */ + if (msgs[i].flags & I2C_M_RD) { + /* Read the data */ + ret = mxc_i2c_readbytes(dev, &msgs[i], (i + 1 == num), + addr_comp); + if (ret < 0) { + dev_err(&dev->adap.dev, "mxc_i2c_readbytes:" + " fail.\n"); + break; + } + } else { + /* Write the data */ + ret = mxc_i2c_writebytes(dev, &msgs[i], (i + 1 == num)); + if (ret < 0) { + dev_err(&dev->adap.dev, "mxc_i2c_writebytes:" + " fail.\n"); + break; + } + } + } + + mxc_i2c_module_dis(dev); + /* + * Decrease by 1 as we do not want Start message to be included in + * the count + */ + return (i < 0 ? ret : i); +} + +/*! + * Returns the i2c functionality supported by this driver. + * + * @param adap adapter structure for this i2c device + * + * @return Returns the functionality that is supported. + */ +static u32 mxc_i2c_func(struct i2c_adapter *adap) +{ + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; +} + +/*! + * Stores the pointers for the i2c algorithm functions. The algorithm functions + * is used by the i2c bus driver to talk to the i2c bus + */ +static struct i2c_algorithm mxc_i2c_algorithm = { + .master_xfer = mxc_i2c_xfer, + .functionality = mxc_i2c_func +}; + +/*! + * Interrupt Service Routine. It signals to the process about the data transfer + * completion. Also sets a flag if bus arbitration is lost. + * @param irq the interrupt number + * @param dev_id driver private data + * + * @return The function returns \b IRQ_HANDLED. + */ +static irqreturn_t mxc_i2c_handler(int irq, void *dev_id) +{ + mxc_i2c_device *dev = dev_id; + volatile unsigned int sr, cr; + + sr = readw(dev->membase + MXC_I2SR); + cr = readw(dev->membase + MXC_I2CR); + + /* + * Clear the interrupt bit + */ + writew(0x0, dev->membase + MXC_I2SR); + + if (sr & MXC_I2SR_IAL) { + dev_err(&dev->adap.dev, "Bus Arbitration lost\n"); + } else { + /* Interrupt due byte transfer completion */ + dev->tx_success = true; + /* Check if RXAK is received in Transmit mode */ + if ((cr & MXC_I2CR_MTX) && (sr & MXC_I2SR_RXAK)) { + dev->tx_success = false; + } + dev->transfer_done = true; + wake_up_interruptible(&dev->wq); + } + + return IRQ_HANDLED; +} + +/*! + * This function is called to put the I2C adapter in a low power state. Refer to the + * document driver-model/driver.txt in the kernel source tree for more + * information. + * + * @param pdev the device structure used to give information on which I2C + * to suspend + * @param state the power state the device is entering + * + * @return The function returns 0 on success and -1 on failure. + */ +static int mxci2c_suspend_noirq(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + mxc_i2c_device *mxcdev = platform_get_drvdata(pdev); + volatile unsigned int sr = 0; + + if (mxcdev == NULL) { + return -1; + } + + /* Prevent further calls to be processed */ + mxcdev->low_power = true; + /* Wait till we finish the current transfer */ + sr = readw(mxcdev->membase + MXC_I2SR); + while (sr & MXC_I2SR_IBB) { + msleep(10); + sr = readw(mxcdev->membase + MXC_I2SR); + } + gpio_i2c_inactive(mxcdev->adap.id); + + return 0; +} + +/*! + * This function is called to bring the I2C adapter back from a low power state. Refer + * to the document driver-model/driver.txt in the kernel source tree for more + * information. + * + * @param pdev the device structure used to give information on which I2C + * to resume + * + * @return The function returns 0 on success and -1 on failure + */ +static int mxci2c_resume_noirq(struct device *dev) +{ + struct platform_device *pdev = to_platform_device(dev); + mxc_i2c_device *mxcdev = platform_get_drvdata(pdev); + + if (mxcdev == NULL) + return -1; + + mxcdev->low_power = false; + gpio_i2c_active(mxcdev->adap.id); + + return 0; +} + +/*! + * This function is called during the driver binding process. + * + * @param pdev the device structure used to store device specific + * information that is used by the suspend, resume and remove + * functions + * + * @return The function always returns 0. + */ +static int mxci2c_probe(struct platform_device *pdev) +{ + mxc_i2c_device *mxc_i2c; + struct mxc_i2c_platform_data *i2c_plat_data = pdev->dev.platform_data; + struct resource *res; + int id = pdev->id; + u32 clk_freq; + int ret = 0; + int i; + + mxc_i2c = kzalloc(sizeof(mxc_i2c_device), GFP_KERNEL); + if (!mxc_i2c) { + return -ENOMEM; + } + + res = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (res == NULL) { + ret = -ENODEV; + goto err1; + } + mxc_i2c->membase = ioremap(res->start, res->end - res->start + 1); + + /* + * Request the I2C interrupt + */ + mxc_i2c->irq = platform_get_irq(pdev, 0); + if (mxc_i2c->irq < 0) { + ret = mxc_i2c->irq; + goto err2; + } + + ret = request_irq(mxc_i2c->irq, mxc_i2c_handler, + 0, pdev->name, mxc_i2c); + if (ret < 0) { + goto err2; + } + + init_waitqueue_head(&mxc_i2c->wq); + + mxc_i2c->low_power = false; + + gpio_i2c_active(id); + + mxc_i2c->clk = clk_get(&pdev->dev, "i2c_clk"); + clk_freq = clk_get_rate(mxc_i2c->clk); + mxc_i2c->clkdiv = -1; + if (i2c_plat_data->i2c_clk) { + /* Calculate divider and round up any fractional part */ + int div = (clk_freq + i2c_plat_data->i2c_clk - 1) / + i2c_plat_data->i2c_clk; + for (i = 0; i2c_clk_table[i].div != 0; i++) { + if (i2c_clk_table[i].div >= div) { + mxc_i2c->clkdiv = i2c_clk_table[i].reg_value; + break; + } + } + } + if (mxc_i2c->clkdiv == -1) { + i--; + mxc_i2c->clkdiv = 0x1F; /* Use max divider */ + } + dev_dbg(&pdev->dev, "i2c speed is %d/%d = %d bps, reg val = 0x%02X\n", + clk_freq, i2c_clk_table[i].div, + clk_freq / i2c_clk_table[i].div, mxc_i2c->clkdiv); + + /* + * Set the adapter information + */ + strlcpy(mxc_i2c->adap.name, pdev->name, 48); + mxc_i2c->adap.id = mxc_i2c->adap.nr = id; + mxc_i2c->adap.algo = &mxc_i2c_algorithm; + mxc_i2c->adap.timeout = 1; + platform_set_drvdata(pdev, mxc_i2c); + i2c_set_adapdata(&mxc_i2c->adap, mxc_i2c); + ret = i2c_add_numbered_adapter(&mxc_i2c->adap); + if (ret < 0) + goto err3; + + printk(KERN_INFO "MXC I2C driver\n"); + return 0; + + err3: + free_irq(mxc_i2c->irq, mxc_i2c); + gpio_i2c_inactive(id); + err2: + iounmap(mxc_i2c->membase); + err1: + dev_err(&pdev->dev, "failed to probe i2c adapter\n"); + kfree(mxc_i2c); + return ret; +} + +/*! + * Dissociates the driver from the I2C device. + * + * @param pdev the device structure used to give information on which I2C + * to remove + * + * @return The function always returns 0. + */ +static int mxci2c_remove(struct platform_device *pdev) +{ + mxc_i2c_device *mxc_i2c = platform_get_drvdata(pdev); + int id = pdev->id; + + free_irq(mxc_i2c->irq, mxc_i2c); + i2c_del_adapter(&mxc_i2c->adap); + gpio_i2c_inactive(id); + clk_put(mxc_i2c->clk); + platform_set_drvdata(pdev, NULL); + iounmap(mxc_i2c->membase); + kfree(mxc_i2c); + return 0; +} + +static struct dev_pm_ops mxci2c_dev_pm_ops = { + .suspend_noirq = mxci2c_suspend_noirq, + .resume_noirq = mxci2c_resume_noirq, +}; + +/*! + * This structure contains pointers to the power management callback functions. + */ +static struct platform_driver mxci2c_driver = { + .driver = { + .name = "mxc_i2c", + .owner = THIS_MODULE, + .pm = &mxci2c_dev_pm_ops, + }, + .probe = mxci2c_probe, + .remove = mxci2c_remove, +}; + +/*! + * Function requests the interrupts and registers the i2c adapter structures. + * + * @return The function returns 0 on success and a non-zero value on failure. + */ +static int __init mxc_i2c_init(void) +{ + /* Register the device driver structure. */ + return platform_driver_register(&mxci2c_driver); +} + +/*! + * This function is used to cleanup all resources before the driver exits. + */ +static void __exit mxc_i2c_exit(void) +{ + platform_driver_unregister(&mxci2c_driver); +} + +subsys_initcall(mxc_i2c_init); +module_exit(mxc_i2c_exit); + +MODULE_AUTHOR("Freescale Semiconductor, Inc."); +MODULE_DESCRIPTION("MXC I2C driver"); +MODULE_LICENSE("GPL"); |