2011-11-08 10:49:46 +00:00
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/*
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* i2c Support for Atmel's AT91 Two-Wire Interface (TWI)
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*
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* Copyright (C) 2011 Weinmann Medical GmbH
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* Author: Nikolaus Voss <n.voss@weinmann.de>
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*
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* Evolved from original work by:
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* Copyright (C) 2004 Rick Bronson
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* Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>
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*
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* Borrowed heavily from original work by:
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* Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/clk.h>
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#include <linux/completion.h>
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/module.h>
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2012-09-12 06:42:14 +00:00
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#include <linux/of.h>
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#include <linux/of_device.h>
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#include <linux/of_i2c.h>
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2011-11-08 10:49:46 +00:00
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#define TWI_CLK_HZ 100000 /* max 400 Kbits/s */
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#define AT91_I2C_TIMEOUT msecs_to_jiffies(100) /* transfer timeout */
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/* AT91 TWI register definitions */
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#define AT91_TWI_CR 0x0000 /* Control Register */
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#define AT91_TWI_START 0x0001 /* Send a Start Condition */
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#define AT91_TWI_STOP 0x0002 /* Send a Stop Condition */
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#define AT91_TWI_MSEN 0x0004 /* Master Transfer Enable */
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#define AT91_TWI_SVDIS 0x0020 /* Slave Transfer Disable */
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2012-11-13 15:43:21 +00:00
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#define AT91_TWI_QUICK 0x0040 /* SMBus quick command */
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2011-11-08 10:49:46 +00:00
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#define AT91_TWI_SWRST 0x0080 /* Software Reset */
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#define AT91_TWI_MMR 0x0004 /* Master Mode Register */
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#define AT91_TWI_IADRSZ_1 0x0100 /* Internal Device Address Size */
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#define AT91_TWI_MREAD 0x1000 /* Master Read Direction */
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#define AT91_TWI_IADR 0x000c /* Internal Address Register */
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#define AT91_TWI_CWGR 0x0010 /* Clock Waveform Generator Reg */
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#define AT91_TWI_SR 0x0020 /* Status Register */
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#define AT91_TWI_TXCOMP 0x0001 /* Transmission Complete */
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#define AT91_TWI_RXRDY 0x0002 /* Receive Holding Register Ready */
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#define AT91_TWI_TXRDY 0x0004 /* Transmit Holding Register Ready */
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#define AT91_TWI_OVRE 0x0040 /* Overrun Error */
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#define AT91_TWI_UNRE 0x0080 /* Underrun Error */
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#define AT91_TWI_NACK 0x0100 /* Not Acknowledged */
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#define AT91_TWI_IER 0x0024 /* Interrupt Enable Register */
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#define AT91_TWI_IDR 0x0028 /* Interrupt Disable Register */
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#define AT91_TWI_IMR 0x002c /* Interrupt Mask Register */
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#define AT91_TWI_RHR 0x0030 /* Receive Holding Register */
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#define AT91_TWI_THR 0x0034 /* Transmit Holding Register */
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struct at91_twi_pdata {
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unsigned clk_max_div;
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unsigned clk_offset;
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bool has_unre_flag;
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};
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struct at91_twi_dev {
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struct device *dev;
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void __iomem *base;
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struct completion cmd_complete;
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struct clk *clk;
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u8 *buf;
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size_t buf_len;
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struct i2c_msg *msg;
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int irq;
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unsigned transfer_status;
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struct i2c_adapter adapter;
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unsigned twi_cwgr_reg;
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struct at91_twi_pdata *pdata;
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};
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static unsigned at91_twi_read(struct at91_twi_dev *dev, unsigned reg)
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{
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return readl_relaxed(dev->base + reg);
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}
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static void at91_twi_write(struct at91_twi_dev *dev, unsigned reg, unsigned val)
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{
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writel_relaxed(val, dev->base + reg);
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}
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static void at91_disable_twi_interrupts(struct at91_twi_dev *dev)
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{
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at91_twi_write(dev, AT91_TWI_IDR,
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AT91_TWI_TXCOMP | AT91_TWI_RXRDY | AT91_TWI_TXRDY);
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}
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static void at91_init_twi_bus(struct at91_twi_dev *dev)
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{
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at91_disable_twi_interrupts(dev);
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SWRST);
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_MSEN);
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_SVDIS);
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at91_twi_write(dev, AT91_TWI_CWGR, dev->twi_cwgr_reg);
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}
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/*
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* Calculate symmetric clock as stated in datasheet:
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* twi_clk = F_MAIN / (2 * (cdiv * (1 << ckdiv) + offset))
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*/
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static void __devinit at91_calc_twi_clock(struct at91_twi_dev *dev, int twi_clk)
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{
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int ckdiv, cdiv, div;
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struct at91_twi_pdata *pdata = dev->pdata;
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int offset = pdata->clk_offset;
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int max_ckdiv = pdata->clk_max_div;
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div = max(0, (int)DIV_ROUND_UP(clk_get_rate(dev->clk),
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2 * twi_clk) - offset);
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ckdiv = fls(div >> 8);
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cdiv = div >> ckdiv;
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if (ckdiv > max_ckdiv) {
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dev_warn(dev->dev, "%d exceeds ckdiv max value which is %d.\n",
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ckdiv, max_ckdiv);
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ckdiv = max_ckdiv;
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cdiv = 255;
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}
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dev->twi_cwgr_reg = (ckdiv << 16) | (cdiv << 8) | cdiv;
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dev_dbg(dev->dev, "cdiv %d ckdiv %d\n", cdiv, ckdiv);
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}
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static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
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{
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if (dev->buf_len <= 0)
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return;
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at91_twi_write(dev, AT91_TWI_THR, *dev->buf);
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/* send stop when last byte has been written */
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if (--dev->buf_len == 0)
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
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dev_dbg(dev->dev, "wrote 0x%x, to go %d\n", *dev->buf, dev->buf_len);
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++dev->buf;
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}
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static void at91_twi_read_next_byte(struct at91_twi_dev *dev)
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{
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if (dev->buf_len <= 0)
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return;
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*dev->buf = at91_twi_read(dev, AT91_TWI_RHR) & 0xff;
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--dev->buf_len;
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/* handle I2C_SMBUS_BLOCK_DATA */
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if (unlikely(dev->msg->flags & I2C_M_RECV_LEN)) {
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dev->msg->flags &= ~I2C_M_RECV_LEN;
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dev->buf_len += *dev->buf;
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dev->msg->len = dev->buf_len + 1;
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dev_dbg(dev->dev, "received block length %d\n", dev->buf_len);
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}
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/* send stop if second but last byte has been read */
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if (dev->buf_len == 1)
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
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dev_dbg(dev->dev, "read 0x%x, to go %d\n", *dev->buf, dev->buf_len);
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++dev->buf;
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}
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static irqreturn_t atmel_twi_interrupt(int irq, void *dev_id)
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{
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struct at91_twi_dev *dev = dev_id;
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const unsigned status = at91_twi_read(dev, AT91_TWI_SR);
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const unsigned irqstatus = status & at91_twi_read(dev, AT91_TWI_IMR);
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if (!irqstatus)
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return IRQ_NONE;
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else if (irqstatus & AT91_TWI_RXRDY)
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at91_twi_read_next_byte(dev);
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else if (irqstatus & AT91_TWI_TXRDY)
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at91_twi_write_next_byte(dev);
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/* catch error flags */
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dev->transfer_status |= status;
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if (irqstatus & AT91_TWI_TXCOMP) {
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at91_disable_twi_interrupts(dev);
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complete(&dev->cmd_complete);
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}
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return IRQ_HANDLED;
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}
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static int at91_do_twi_transfer(struct at91_twi_dev *dev)
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{
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int ret;
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bool has_unre_flag = dev->pdata->has_unre_flag;
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dev_dbg(dev->dev, "transfer: %s %d bytes.\n",
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(dev->msg->flags & I2C_M_RD) ? "read" : "write", dev->buf_len);
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INIT_COMPLETION(dev->cmd_complete);
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dev->transfer_status = 0;
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2012-11-13 15:43:21 +00:00
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if (!dev->buf_len) {
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at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_QUICK);
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at91_twi_write(dev, AT91_TWI_IER, AT91_TWI_TXCOMP);
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} else if (dev->msg->flags & I2C_M_RD) {
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2011-11-08 10:49:46 +00:00
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unsigned start_flags = AT91_TWI_START;
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if (at91_twi_read(dev, AT91_TWI_SR) & AT91_TWI_RXRDY) {
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dev_err(dev->dev, "RXRDY still set!");
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at91_twi_read(dev, AT91_TWI_RHR);
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}
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/* if only one byte is to be read, immediately stop transfer */
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if (dev->buf_len <= 1 && !(dev->msg->flags & I2C_M_RECV_LEN))
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start_flags |= AT91_TWI_STOP;
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at91_twi_write(dev, AT91_TWI_CR, start_flags);
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at91_twi_write(dev, AT91_TWI_IER,
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AT91_TWI_TXCOMP | AT91_TWI_RXRDY);
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} else {
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at91_twi_write_next_byte(dev);
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at91_twi_write(dev, AT91_TWI_IER,
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AT91_TWI_TXCOMP | AT91_TWI_TXRDY);
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}
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ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
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dev->adapter.timeout);
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if (ret == 0) {
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dev_err(dev->dev, "controller timed out\n");
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at91_init_twi_bus(dev);
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return -ETIMEDOUT;
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}
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if (dev->transfer_status & AT91_TWI_NACK) {
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dev_dbg(dev->dev, "received nack\n");
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return -EREMOTEIO;
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}
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if (dev->transfer_status & AT91_TWI_OVRE) {
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dev_err(dev->dev, "overrun while reading\n");
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return -EIO;
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}
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if (has_unre_flag && dev->transfer_status & AT91_TWI_UNRE) {
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dev_err(dev->dev, "underrun while writing\n");
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return -EIO;
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}
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dev_dbg(dev->dev, "transfer complete\n");
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return 0;
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}
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static int at91_twi_xfer(struct i2c_adapter *adap, struct i2c_msg *msg, int num)
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{
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struct at91_twi_dev *dev = i2c_get_adapdata(adap);
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int ret;
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unsigned int_addr_flag = 0;
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struct i2c_msg *m_start = msg;
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dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);
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/*
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* The hardware can handle at most two messages concatenated by a
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* repeated start via it's internal address feature.
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*/
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if (num > 2) {
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dev_err(dev->dev,
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"cannot handle more than two concatenated messages.\n");
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return 0;
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} else if (num == 2) {
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int internal_address = 0;
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int i;
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if (msg->flags & I2C_M_RD) {
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dev_err(dev->dev, "first transfer must be write.\n");
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return -EINVAL;
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}
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if (msg->len > 3) {
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dev_err(dev->dev, "first message size must be <= 3.\n");
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return -EINVAL;
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}
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/* 1st msg is put into the internal address, start with 2nd */
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m_start = &msg[1];
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for (i = 0; i < msg->len; ++i) {
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const unsigned addr = msg->buf[msg->len - 1 - i];
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internal_address |= addr << (8 * i);
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int_addr_flag += AT91_TWI_IADRSZ_1;
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}
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at91_twi_write(dev, AT91_TWI_IADR, internal_address);
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}
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at91_twi_write(dev, AT91_TWI_MMR, (m_start->addr << 16) | int_addr_flag
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| ((m_start->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));
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dev->buf_len = m_start->len;
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dev->buf = m_start->buf;
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dev->msg = m_start;
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ret = at91_do_twi_transfer(dev);
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return (ret < 0) ? ret : num;
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}
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static u32 at91_twi_func(struct i2c_adapter *adapter)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL
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| I2C_FUNC_SMBUS_READ_BLOCK_DATA;
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}
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static struct i2c_algorithm at91_twi_algorithm = {
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.master_xfer = at91_twi_xfer,
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.functionality = at91_twi_func,
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};
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static struct at91_twi_pdata at91rm9200_config = {
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.clk_max_div = 5,
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.clk_offset = 3,
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.has_unre_flag = true,
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};
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static struct at91_twi_pdata at91sam9261_config = {
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.clk_max_div = 5,
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.clk_offset = 4,
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|
|
.has_unre_flag = false,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct at91_twi_pdata at91sam9260_config = {
|
|
|
|
.clk_max_div = 7,
|
|
|
|
.clk_offset = 4,
|
|
|
|
.has_unre_flag = false,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct at91_twi_pdata at91sam9g20_config = {
|
|
|
|
.clk_max_div = 7,
|
|
|
|
.clk_offset = 4,
|
|
|
|
.has_unre_flag = false,
|
|
|
|
};
|
|
|
|
|
|
|
|
static struct at91_twi_pdata at91sam9g10_config = {
|
|
|
|
.clk_max_div = 7,
|
|
|
|
.clk_offset = 4,
|
|
|
|
.has_unre_flag = false,
|
|
|
|
};
|
|
|
|
|
2012-09-12 06:42:14 +00:00
|
|
|
static struct at91_twi_pdata at91sam9x5_config = {
|
|
|
|
.clk_max_div = 7,
|
|
|
|
.clk_offset = 4,
|
|
|
|
.has_unre_flag = false,
|
|
|
|
};
|
|
|
|
|
2011-11-08 10:49:46 +00:00
|
|
|
static const struct platform_device_id at91_twi_devtypes[] = {
|
|
|
|
{
|
|
|
|
.name = "i2c-at91rm9200",
|
|
|
|
.driver_data = (unsigned long) &at91rm9200_config,
|
|
|
|
}, {
|
|
|
|
.name = "i2c-at91sam9261",
|
|
|
|
.driver_data = (unsigned long) &at91sam9261_config,
|
|
|
|
}, {
|
|
|
|
.name = "i2c-at91sam9260",
|
|
|
|
.driver_data = (unsigned long) &at91sam9260_config,
|
|
|
|
}, {
|
|
|
|
.name = "i2c-at91sam9g20",
|
|
|
|
.driver_data = (unsigned long) &at91sam9g20_config,
|
|
|
|
}, {
|
|
|
|
.name = "i2c-at91sam9g10",
|
|
|
|
.driver_data = (unsigned long) &at91sam9g10_config,
|
|
|
|
}, {
|
|
|
|
/* sentinel */
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
2012-09-12 06:42:14 +00:00
|
|
|
#if defined(CONFIG_OF)
|
|
|
|
static const struct of_device_id atmel_twi_dt_ids[] = {
|
|
|
|
{
|
|
|
|
.compatible = "atmel,at91sam9260-i2c",
|
|
|
|
.data = &at91sam9260_config,
|
|
|
|
} , {
|
|
|
|
.compatible = "atmel,at91sam9g20-i2c",
|
|
|
|
.data = &at91sam9g20_config,
|
|
|
|
} , {
|
|
|
|
.compatible = "atmel,at91sam9g10-i2c",
|
|
|
|
.data = &at91sam9g10_config,
|
|
|
|
}, {
|
|
|
|
.compatible = "atmel,at91sam9x5-i2c",
|
|
|
|
.data = &at91sam9x5_config,
|
|
|
|
}, {
|
|
|
|
/* sentinel */
|
|
|
|
}
|
|
|
|
};
|
|
|
|
MODULE_DEVICE_TABLE(of, atmel_twi_dt_ids);
|
|
|
|
#else
|
|
|
|
#define atmel_twi_dt_ids NULL
|
|
|
|
#endif
|
|
|
|
|
|
|
|
static struct at91_twi_pdata * __devinit at91_twi_get_driver_data(
|
|
|
|
struct platform_device *pdev)
|
|
|
|
{
|
|
|
|
if (pdev->dev.of_node) {
|
|
|
|
const struct of_device_id *match;
|
|
|
|
match = of_match_node(atmel_twi_dt_ids, pdev->dev.of_node);
|
|
|
|
if (!match)
|
|
|
|
return NULL;
|
|
|
|
return match->data;
|
|
|
|
}
|
|
|
|
return (struct at91_twi_pdata *) platform_get_device_id(pdev)->driver_data;
|
|
|
|
}
|
|
|
|
|
2011-11-08 10:49:46 +00:00
|
|
|
static int __devinit at91_twi_probe(struct platform_device *pdev)
|
|
|
|
{
|
|
|
|
struct at91_twi_dev *dev;
|
|
|
|
struct resource *mem;
|
|
|
|
int rc;
|
|
|
|
|
|
|
|
dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
|
|
|
|
if (!dev)
|
|
|
|
return -ENOMEM;
|
|
|
|
init_completion(&dev->cmd_complete);
|
|
|
|
dev->dev = &pdev->dev;
|
|
|
|
|
|
|
|
mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
|
|
|
|
if (!mem)
|
|
|
|
return -ENODEV;
|
|
|
|
|
|
|
|
dev->pdata = at91_twi_get_driver_data(pdev);
|
|
|
|
if (!dev->pdata)
|
|
|
|
return -ENODEV;
|
|
|
|
|
|
|
|
dev->base = devm_request_and_ioremap(&pdev->dev, mem);
|
|
|
|
if (!dev->base)
|
|
|
|
return -EBUSY;
|
|
|
|
|
|
|
|
dev->irq = platform_get_irq(pdev, 0);
|
|
|
|
if (dev->irq < 0)
|
|
|
|
return dev->irq;
|
|
|
|
|
|
|
|
rc = devm_request_irq(&pdev->dev, dev->irq, atmel_twi_interrupt, 0,
|
|
|
|
dev_name(dev->dev), dev);
|
|
|
|
if (rc) {
|
|
|
|
dev_err(dev->dev, "Cannot get irq %d: %d\n", dev->irq, rc);
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
|
|
|
|
platform_set_drvdata(pdev, dev);
|
|
|
|
|
|
|
|
dev->clk = devm_clk_get(dev->dev, NULL);
|
|
|
|
if (IS_ERR(dev->clk)) {
|
|
|
|
dev_err(dev->dev, "no clock defined\n");
|
|
|
|
return -ENODEV;
|
|
|
|
}
|
|
|
|
clk_prepare_enable(dev->clk);
|
|
|
|
|
|
|
|
at91_calc_twi_clock(dev, TWI_CLK_HZ);
|
|
|
|
at91_init_twi_bus(dev);
|
|
|
|
|
|
|
|
snprintf(dev->adapter.name, sizeof(dev->adapter.name), "AT91");
|
|
|
|
i2c_set_adapdata(&dev->adapter, dev);
|
|
|
|
dev->adapter.owner = THIS_MODULE;
|
|
|
|
dev->adapter.class = I2C_CLASS_HWMON;
|
|
|
|
dev->adapter.algo = &at91_twi_algorithm;
|
|
|
|
dev->adapter.dev.parent = dev->dev;
|
|
|
|
dev->adapter.nr = pdev->id;
|
|
|
|
dev->adapter.timeout = AT91_I2C_TIMEOUT;
|
2012-09-12 06:42:14 +00:00
|
|
|
dev->adapter.dev.of_node = pdev->dev.of_node;
|
2011-11-08 10:49:46 +00:00
|
|
|
|
|
|
|
rc = i2c_add_numbered_adapter(&dev->adapter);
|
|
|
|
if (rc) {
|
|
|
|
dev_err(dev->dev, "Adapter %s registration failed\n",
|
|
|
|
dev->adapter.name);
|
|
|
|
clk_disable_unprepare(dev->clk);
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
|
2012-09-12 06:42:14 +00:00
|
|
|
of_i2c_register_devices(&dev->adapter);
|
|
|
|
|
2011-11-08 10:49:46 +00:00
|
|
|
dev_info(dev->dev, "AT91 i2c bus driver.\n");
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int __devexit at91_twi_remove(struct platform_device *pdev)
|
|
|
|
{
|
|
|
|
struct at91_twi_dev *dev = platform_get_drvdata(pdev);
|
|
|
|
int rc;
|
|
|
|
|
|
|
|
rc = i2c_del_adapter(&dev->adapter);
|
|
|
|
clk_disable_unprepare(dev->clk);
|
|
|
|
|
|
|
|
return rc;
|
|
|
|
}
|
|
|
|
|
|
|
|
#ifdef CONFIG_PM
|
|
|
|
|
|
|
|
static int at91_twi_runtime_suspend(struct device *dev)
|
|
|
|
{
|
|
|
|
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
|
|
|
|
|
|
|
|
clk_disable(twi_dev->clk);
|
|
|
|
|
|
|
|
return 0;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int at91_twi_runtime_resume(struct device *dev)
|
|
|
|
{
|
|
|
|
struct at91_twi_dev *twi_dev = dev_get_drvdata(dev);
|
|
|
|
|
|
|
|
return clk_enable(twi_dev->clk);
|
|
|
|
}
|
|
|
|
|
|
|
|
static const struct dev_pm_ops at91_twi_pm = {
|
|
|
|
.runtime_suspend = at91_twi_runtime_suspend,
|
|
|
|
.runtime_resume = at91_twi_runtime_resume,
|
|
|
|
};
|
|
|
|
|
|
|
|
#define at91_twi_pm_ops (&at91_twi_pm)
|
|
|
|
#else
|
|
|
|
#define at91_twi_pm_ops NULL
|
|
|
|
#endif
|
|
|
|
|
|
|
|
static struct platform_driver at91_twi_driver = {
|
|
|
|
.probe = at91_twi_probe,
|
|
|
|
.remove = __devexit_p(at91_twi_remove),
|
|
|
|
.id_table = at91_twi_devtypes,
|
|
|
|
.driver = {
|
|
|
|
.name = "at91_i2c",
|
|
|
|
.owner = THIS_MODULE,
|
2012-09-12 06:42:14 +00:00
|
|
|
.of_match_table = atmel_twi_dt_ids,
|
2011-11-08 10:49:46 +00:00
|
|
|
.pm = at91_twi_pm_ops,
|
|
|
|
},
|
|
|
|
};
|
|
|
|
|
|
|
|
static int __init at91_twi_init(void)
|
|
|
|
{
|
|
|
|
return platform_driver_register(&at91_twi_driver);
|
|
|
|
}
|
|
|
|
|
|
|
|
static void __exit at91_twi_exit(void)
|
|
|
|
{
|
|
|
|
platform_driver_unregister(&at91_twi_driver);
|
|
|
|
}
|
|
|
|
|
|
|
|
subsys_initcall(at91_twi_init);
|
|
|
|
module_exit(at91_twi_exit);
|
|
|
|
|
|
|
|
MODULE_AUTHOR("Nikolaus Voss <n.voss@weinmann.de>");
|
|
|
|
MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
|
|
|
|
MODULE_LICENSE("GPL");
|
|
|
|
MODULE_ALIAS("platform:at91_i2c");
|