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    SubjectRe: [PATCH] i2c: adds support for i2c bus on Freescale CPM1/CPM2 controllers
    Hi Jochen,

    On Wed, May 21, 2008 at 12:43:22PM +0200, Jochen Friedrich wrote:
    > This driver uses the port of 2.4 code from Vitaly Bordug
    > <vitb@kernel.crashing.org> and the actual algorithm used by the i2c
    > driver of the DBox code on cvs.tuxboc.org from Felix Domke
    > (tmbinc@gmx.net) and Gillem (htoa@gmx.net) converted to an
    > of_platform_driver. Tested on CPM1 (MPC823 on dbox2 hardware) and
    > CPM2 (MPC8272).
    >
    > Signed-off-by: Jochen Friedrich <jochen@scram.de>
    > ---
    Works on MPC8260.

    Tested-by: Wolfram Sang <w.sang@pengutronix.de>

    > drivers/i2c/busses/Kconfig | 10 +
    > drivers/i2c/busses/Makefile | 1 +
    > drivers/i2c/busses/i2c-cpm.c | 745 ++++++++++++++++++++++++++++++++++++++++++
    > 3 files changed, 756 insertions(+), 0 deletions(-)
    > create mode 100644 drivers/i2c/busses/i2c-cpm.c
    >
    > Changes since last version:
    > - fixed copy and paste bug (I2COM_MASTER -> I2COM_START)
    > - changed dev_err() to dev_dbg() for NACK
    > - changed dev_dbg() to dev_err() for Timeout
    > - added explanation for brg formular
    Typo: formula

    > - added "bus-frequency" OF attribute to be able to override i2c clock
    \o/ Cool feature. Worked nicely.

    > - support for numbered adapter (it was already documented in
    > my booting-without-of patch but not yet implemented)
    > - finally changed i2c "pseudo address" 0xfe to 0x7f << 1
    > - get rid of the "fsl,cpm-i2c" name. This logic was screwed
    > - fixed the error patch for request_irq failure
    path instead of patch? But well, I assume typos in this section do not
    matter much anyhow as they are not imported into git. Am I right, Jean?

    > - s/IIC/I2C/g
    > - fixed error output "read timeout" -> "transfer timeout"
    >
    > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
    > index 48438cc..c627b94 100644
    > --- a/drivers/i2c/busses/Kconfig
    > +++ b/drivers/i2c/busses/Kconfig
    > @@ -117,6 +117,16 @@ config I2C_BLACKFIN_TWI_CLK_KHZ
    > help
    > The unit of the TWI clock is kHz.
    >
    > +config I2C_CPM
    > + tristate "Freescale CPM1 or CPM2 (MPC8xx/826x)"
    > + depends on (CPM1 || CPM2) && OF_I2C
    > + help
    > + This supports the use of the I2C interface on Freescale
    > + processors with CPM1 or CPM2.
    > +
    > + This driver can also be built as a module. If so, the module
    > + will be called i2c-cpm.
    > +
    > config I2C_DAVINCI
    > tristate "DaVinci I2C driver"
    > depends on ARCH_DAVINCI
    > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
    > index e8c882a..1ccd5ba 100644
    > --- a/drivers/i2c/busses/Makefile
    > +++ b/drivers/i2c/busses/Makefile
    > @@ -11,6 +11,7 @@ obj-$(CONFIG_I2C_AMD8111) += i2c-amd8111.o
    > obj-$(CONFIG_I2C_AT91) += i2c-at91.o
    > obj-$(CONFIG_I2C_AU1550) += i2c-au1550.o
    > obj-$(CONFIG_I2C_BLACKFIN_TWI) += i2c-bfin-twi.o
    > +obj-$(CONFIG_I2C_CPM) += i2c-cpm.o
    > obj-$(CONFIG_I2C_DAVINCI) += i2c-davinci.o
    > obj-$(CONFIG_I2C_ELEKTOR) += i2c-elektor.o
    > obj-$(CONFIG_I2C_GPIO) += i2c-gpio.o
    > diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c
    > new file mode 100644
    > index 0000000..305159c
    > --- /dev/null
    > +++ b/drivers/i2c/busses/i2c-cpm.c
    > @@ -0,0 +1,745 @@
    > +/*
    > + * Freescale CPM1/CPM2 I2C interface.
    > + * Copyright (c) 1999 Dan Malek (dmalek@jlc.net).
    > + *
    > + * moved into proper i2c interface;
    > + * Brad Parker (brad@heeltoe.com)
    > + *
    > + * Parts from dbox2_i2c.c (cvs.tuxbox.org)
    > + * (C) 2000-2001 Felix Domke (tmbinc@gmx.net), Gillem (htoa@gmx.net)
    > + *
    > + * (C) 2007 Montavista Software, Inc.
    > + * Vitaly Bordug <vitb@kernel.crashing.org>
    > + *
    > + * Converted to of_platform_device. Renamed to i2c-cpm.c.
    > + * (C) 2007,2008 Jochen Friedrich <jochen@scram.de>
    > + *
    > + * This program is free software; you can redistribute it and/or modify
    > + * it under the terms of the GNU General Public License as published by
    > + * the Free Software Foundation; either version 2 of the License, or
    > + * (at your option) any later version.
    > + *
    > + * This program is distributed in the hope that it will be useful,
    > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
    > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
    > + * GNU General Public License for more details.
    > + *
    > + * You should have received a copy of the GNU General Public License
    > + * along with this program; if not, write to the Free Software
    > + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
    > + */
    > +
    > +#include <linux/kernel.h>
    > +#include <linux/module.h>
    > +#include <linux/delay.h>
    > +#include <linux/slab.h>
    > +#include <linux/init.h>
    > +#include <linux/interrupt.h>
    > +#include <linux/errno.h>
    > +#include <linux/stddef.h>
    > +#include <linux/i2c.h>
    > +#include <linux/io.h>
    > +#include <linux/dma-mapping.h>
    > +#include <linux/of_device.h>
    > +#include <linux/of_platform.h>
    > +#include <linux/of_i2c.h>
    > +#include <sysdev/fsl_soc.h>
    > +#include <asm/cpm.h>
    > +
    > +/* Try to define this if you have an older CPU (earlier than rev D4) */
    > +/* However, better use a GPIO based bitbang driver in this case :/ */
    > +#undef I2C_CHIP_ERRATA
    > +
    > +#define CPM_MAX_READ 513
    > +#define CPM_MAXBD 4
    > +
    > +#define I2C_EB (0x10) /* Big endian mode */
    > +#define I2C_EB_CPM2 (0x30) /* Big endian mode, memory snoop */
    > +
    > +#define DPRAM_BASE ((u8 __iomem __force *)cpm_muram_addr(0))
    > +
    > +/* I2C parameter RAM. */
    > +struct i2c_ram {
    > + ushort rbase; /* Rx Buffer descriptor base address */
    > + ushort tbase; /* Tx Buffer descriptor base address */
    > + u_char rfcr; /* Rx function code */
    > + u_char tfcr; /* Tx function code */
    > + ushort mrblr; /* Max receive buffer length */
    > + uint rstate; /* Internal */
    > + uint rdp; /* Internal */
    > + ushort rbptr; /* Rx Buffer descriptor pointer */
    > + ushort rbc; /* Internal */
    > + uint rxtmp; /* Internal */
    > + uint tstate; /* Internal */
    > + uint tdp; /* Internal */
    > + ushort tbptr; /* Tx Buffer descriptor pointer */
    > + ushort tbc; /* Internal */
    > + uint txtmp; /* Internal */
    > + char res1[4]; /* Reserved */
    > + ushort rpbase; /* Relocation pointer */
    > + char res2[2]; /* Reserved */
    > +};
    > +
    > +#define I2COM_START 0x80
    > +#define I2COM_MASTER 0x01
    > +#define I2CER_TXE 0x10
    > +#define I2CER_BUSY 0x04
    > +#define I2CER_TXB 0x02
    > +#define I2CER_RXB 0x01
    > +#define I2MOD_EN 0x01
    > +
    > +/* I2C Registers */
    > +struct i2c_reg {
    > + u8 i2mod;
    > + u8 res1[3];
    > + u8 i2add;
    > + u8 res2[3];
    > + u8 i2brg;
    > + u8 res3[3];
    > + u8 i2com;
    > + u8 res4[3];
    > + u8 i2cer;
    > + u8 res5[3];
    > + u8 i2cmr;
    > +};
    > +
    > +struct cpm_i2c {
    > + char *base;
    > + struct of_device *ofdev;
    > + struct i2c_adapter adap;
    > + uint dp_addr;
    > + int version; /* CPM1=1, CPM2=2 */
    > + int irq;
    > + int cp_command;
    > + int freq;
    > + struct i2c_reg __iomem *i2c_reg;
    > + struct i2c_ram __iomem *i2c_ram;
    > + u16 i2c_addr;
    > + wait_queue_head_t i2c_wait;
    > + cbd_t __iomem *tbase;
    > + cbd_t __iomem *rbase;
    > + u_char *txbuf[CPM_MAXBD];
    > + u_char *rxbuf[CPM_MAXBD];
    > + u32 txdma[CPM_MAXBD];
    > + u32 rxdma[CPM_MAXBD];
    > +};
    > +
    > +static irqreturn_t cpm_i2c_interrupt(int irq, void *dev_id)
    > +{
    > + struct cpm_i2c *cpm;
    > + struct i2c_reg __iomem *i2c_reg;
    > + struct i2c_adapter *adap = dev_id;
    > + int i;
    > +
    > + cpm = i2c_get_adapdata(dev_id);
    > + i2c_reg = cpm->i2c_reg;
    > +
    > + /* Clear interrupt. */
    > + i = in_8(&i2c_reg->i2cer);
    > + out_8(&i2c_reg->i2cer, i);
    > +
    > + dev_dbg(&adap->dev, "Interrupt: %x\n", i);
    > +
    > + wake_up_interruptible(&cpm->i2c_wait);
    > +
    > + return i ? IRQ_HANDLED : IRQ_NONE;
    > +}
    > +
    > +static void cpm_reset_i2c_params(struct cpm_i2c *cpm)
    > +{
    > + struct i2c_ram __iomem *i2c_ram = cpm->i2c_ram;
    > +
    > + /* Set up the I2C parameters in the parameter ram. */
    > + out_be16(&i2c_ram->tbase, (u8 __iomem *)cpm->tbase - DPRAM_BASE);
    > + out_be16(&i2c_ram->rbase, (u8 __iomem *)cpm->rbase - DPRAM_BASE);
    > +
    > + if (cpm->version == 1) {
    > + out_8(&i2c_ram->tfcr, I2C_EB);
    > + out_8(&i2c_ram->rfcr, I2C_EB);
    > + } else {
    > + out_8(&i2c_ram->tfcr, I2C_EB_CPM2);
    > + out_8(&i2c_ram->rfcr, I2C_EB_CPM2);
    > + }
    > +
    > + out_be16(&i2c_ram->mrblr, CPM_MAX_READ);
    > +
    > + out_be32(&i2c_ram->rstate, 0);
    > + out_be32(&i2c_ram->rdp, 0);
    > + out_be16(&i2c_ram->rbptr, 0);
    > + out_be16(&i2c_ram->rbc, 0);
    > + out_be32(&i2c_ram->rxtmp, 0);
    > + out_be32(&i2c_ram->tstate, 0);
    > + out_be32(&i2c_ram->tdp, 0);
    > + out_be16(&i2c_ram->tbptr, 0);
    > + out_be16(&i2c_ram->tbc, 0);
    > + out_be32(&i2c_ram->txtmp, 0);
    > +}
    > +
    > +static void cpm_i2c_force_close(struct i2c_adapter *adap)
    > +{
    > + struct cpm_i2c *cpm = i2c_get_adapdata(adap);
    > + struct i2c_reg __iomem *i2c_reg = cpm->i2c_reg;
    > +
    > + dev_dbg(&adap->dev, "cpm_i2c_force_close()\n");
    > +
    > + cpm_command(cpm->cp_command, CPM_CR_CLOSE_RX_BD);
    > +
    > + out_8(&i2c_reg->i2cmr, 0x00); /* Disable all interrupts */
    > + out_8(&i2c_reg->i2cer, 0xff);
    > +}
    > +
    > +static void cpm_i2c_parse_message(struct i2c_adapter *adap,
    > + struct i2c_msg *pmsg, int num, int tx, int rx)
    > +{
    > + cbd_t __iomem *tbdf;
    > + cbd_t __iomem *rbdf;
    > + u_char addr;
    > + u_char *tb;
    > + u_char *rb;
    > + struct cpm_i2c *cpm = i2c_get_adapdata(adap);
    > +
    > + tbdf = cpm->tbase + tx;
    > + rbdf = cpm->rbase + rx;
    > +
    > + addr = pmsg->addr << 1;
    > + if (pmsg->flags & I2C_M_RD)
    > + addr |= 1;
    > +
    > + tb = cpm->txbuf[tx];
    > + rb = cpm->rxbuf[rx];
    > +
    > + /* Align read buffer */
    > + rb = (u_char *) (((ulong) rb + 1) & ~1);
    > +
    > + tb[0] = addr; /* Device address byte w/rw flag */
    > +
    > + out_be16(&tbdf->cbd_datlen, pmsg->len + 1);
    > + out_be16(&tbdf->cbd_sc, 0);
    > +
    > + if (!(pmsg->flags & I2C_M_NOSTART))
    > + setbits16(&tbdf->cbd_sc, BD_I2C_START);
    > +
    > + if (tx + 1 == num)
    > + setbits16(&tbdf->cbd_sc, BD_SC_LAST | BD_SC_WRAP);
    > +
    > + if (pmsg->flags & I2C_M_RD) {
    > + /*
    > + * To read, we need an empty buffer of the proper length.
    > + * All that is used is the first byte for address, the remainder
    > + * is just used for timing (and doesn't really have to exist).
    > + */
    > +
    > + dev_dbg(&adap->dev, "cpm_i2c_read(abyte=0x%x)\n", addr);
    > +
    > + out_be16(&rbdf->cbd_datlen, 0);
    > + out_be16(&rbdf->cbd_sc, BD_SC_EMPTY | BD_SC_INTRPT);
    > +
    > + if (rx + 1 == CPM_MAXBD)
    > + setbits16(&rbdf->cbd_sc, BD_SC_WRAP);
    > +
    > + eieio();
    > + setbits16(&tbdf->cbd_sc, BD_SC_READY);
    > + } else {
    > + dev_dbg(&adap->dev, "cpm_iic_write(abyte=0x%x)\n", addr);
    > +
    > + memcpy(tb+1, pmsg->buf, pmsg->len);
    > +
    > + eieio();
    > + setbits16(&tbdf->cbd_sc, BD_SC_READY | BD_SC_INTRPT);
    > + }
    > +}
    > +
    > +static int cpm_i2c_check_message(struct i2c_adapter *adap,
    > + struct i2c_msg *pmsg, int tx, int rx)
    > +{
    > + cbd_t __iomem *tbdf;
    > + cbd_t __iomem *rbdf;
    > + u_char *tb;
    > + u_char *rb;
    > + struct cpm_i2c *cpm = i2c_get_adapdata(adap);
    > +
    > + tbdf = cpm->tbase + tx;
    > + rbdf = cpm->rbase + rx;
    > +
    > + tb = cpm->txbuf[tx];
    > + rb = cpm->rxbuf[rx];
    > +
    > + /* Align read buffer */
    > + rb = (u_char *) (((uint) rb + 1) & ~1);
    > +
    > + eieio();
    > + if (pmsg->flags & I2C_M_RD) {
    > + dev_dbg(&adap->dev, "tx sc 0x%04x, rx sc 0x%04x\n",
    > + in_be16(&tbdf->cbd_sc), in_be16(&rbdf->cbd_sc));
    > +
    > + if (in_be16(&tbdf->cbd_sc) & BD_SC_NAK) {
    > + dev_dbg(&adap->dev, "I2C read; No ack\n");
    > + return -ENXIO;
    > + }
    > + if (in_be16(&rbdf->cbd_sc) & BD_SC_EMPTY) {
    > + dev_err(&adap->dev,
    > + "I2C read; complete but rbuf empty\n");
    > + return -EREMOTEIO;
    > + }
    > + if (in_be16(&rbdf->cbd_sc) & BD_SC_OV) {
    > + dev_err(&adap->dev, "I2C read; Overrun\n");
    > + return -EREMOTEIO;
    > + }
    > + memcpy(pmsg->buf, rb, pmsg->len);
    > + } else {
    > + dev_dbg(&adap->dev, "tx sc %d 0x%04x\n", tx,
    > + in_be16(&tbdf->cbd_sc));
    > +
    > + if (in_be16(&tbdf->cbd_sc) & BD_SC_NAK) {
    > + dev_dbg(&adap->dev, "I2C write; No ack\n");
    > + return -ENXIO;
    > + }
    > + if (in_be16(&tbdf->cbd_sc) & BD_SC_UN) {
    > + dev_err(&adap->dev, "I2C write; Underrun\n");
    > + return -EIO;
    > + }
    > + if (in_be16(&tbdf->cbd_sc) & BD_SC_CL) {
    > + dev_err(&adap->dev, "I2C write; Collision\n");
    > + return -EIO;
    > + }
    > + }
    > + return 0;
    > +}
    > +
    > +static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
    > +{
    > + struct cpm_i2c *cpm = i2c_get_adapdata(adap);
    > + struct i2c_reg __iomem *i2c_reg = cpm->i2c_reg;
    > + struct i2c_ram __iomem *i2c_ram = cpm->i2c_ram;
    > + struct i2c_msg *pmsg;
    > + int ret, i;
    > + int tptr;
    > + int rptr;
    > + cbd_t __iomem *tbdf;
    > + cbd_t __iomem *rbdf;
    > +
    > + if (num > CPM_MAXBD)
    > + return -EINVAL;
    > +
    > + /* Check if we have any oversized READ requests */
    > + for (i = 0; i < num; i++) {
    > + pmsg = &msgs[i];
    > + if (pmsg->len >= CPM_MAX_READ)
    > + return -EINVAL;
    > + }
    > +
    > + /* Reset to use first buffer */
    > + out_be16(&i2c_ram->rbptr, in_be16(&i2c_ram->rbase));
    > + out_be16(&i2c_ram->tbptr, in_be16(&i2c_ram->tbase));
    > +
    > + tbdf = cpm->tbase;
    > + rbdf = cpm->rbase;
    > +
    > + tptr = 0;
    > + rptr = 0;
    > +
    > + while (tptr < num) {
    > + pmsg = &msgs[tptr];
    > + dev_dbg(&adap->dev, "R: %d T: %d\n", rptr, tptr);
    > +
    > + cpm_i2c_parse_message(adap, pmsg, num, tptr, rptr);
    > + if (pmsg->flags & I2C_M_RD)
    > + rptr++;
    > + tptr++;
    > + }
    > + /* Start transfer now */
    > + /* Enable RX/TX/Error interupts */
    > + out_8(&i2c_reg->i2cmr, I2CER_BUSY | I2CER_TXB | I2CER_RXB);
    > + out_8(&i2c_reg->i2cer, 0xff); /* Clear interrupt status */
    > + /* Chip bug, set enable here */
    > + setbits8(&i2c_reg->i2mod, I2MOD_EN); /* Enable */
    > + /* Begin transmission */
    > + setbits8(&i2c_reg->i2com, I2COM_START);
    > +
    > + tptr = 0;
    > + rptr = 0;
    > +
    > + while (tptr < num) {
    > + /* Check for outstanding messages */
    > + dev_dbg(&adap->dev, "test ready.\n");
    > + pmsg = &msgs[tptr];
    > + if (pmsg->flags & I2C_M_RD)
    > + ret = wait_event_interruptible_timeout(cpm->i2c_wait,
    > + !(in_be16(&rbdf[rptr].cbd_sc) & BD_SC_EMPTY),
    > + 1 * HZ);
    > + else
    > + ret = wait_event_interruptible_timeout(cpm->i2c_wait,
    > + !(in_be16(&tbdf[tptr].cbd_sc) & BD_SC_READY),
    > + 1 * HZ);
    > + if (ret == 0) {
    > + ret = -EREMOTEIO;
    > + dev_err(&adap->dev, "I2C transfer: timeout\n");
    > + goto out_err;
    > + }
    > + if (ret > 0) {
    > + dev_dbg(&adap->dev, "ready.\n");
    > + ret = cpm_i2c_check_message(adap, pmsg, tptr, rptr);
    > + tptr++;
    > + if (pmsg->flags & I2C_M_RD)
    > + rptr++;
    > + if (ret)
    > + goto out_err;
    > + }
    > + }
    > +#ifdef I2C_CHIP_ERRATA
    > + /*
    > + * Chip errata, clear enable. This is not needed on rev D4 CPUs.
    > + * Disabling I2C too early may cause too short stop condition
    > + */
    > + udelay(4);
    > + clrbits8(&i2c_reg->i2mod, I2MOD_EN);
    > +#endif
    > + return (num);
    > +
    > +out_err:
    > + cpm_i2c_force_close(adap);
    > +#ifdef I2C_CHIP_ERRATA
    > + /*
    > + * Chip errata, clear enable. This is not needed on rev D4 CPUs.
    > + */
    > + clrbits8(&i2c_reg->i2mod, I2MOD_EN);
    > +#endif
    > + return ret;
    > +}
    > +
    > +static u32 cpm_i2c_func(struct i2c_adapter *adap)
    > +{
    > + return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
    > +}
    > +
    > +/* -----exported algorithm data: ------------------------------------- */
    > +
    > +static const struct i2c_algorithm cpm_i2c_algo = {
    > + .master_xfer = cpm_i2c_xfer,
    > + .functionality = cpm_i2c_func,
    > +};
    > +
    > +static const struct i2c_adapter cpm_ops = {
    > + .owner = THIS_MODULE,
    > + .name = "i2c-cpm",
    > + .algo = &cpm_i2c_algo,
    > + .class = I2C_CLASS_HWMON,
    > +};
    > +
    > +static int __devinit cpm_i2c_setup(struct cpm_i2c *cpm)
    > +{
    > + struct of_device *ofdev = cpm->ofdev;
    > + const u32 *data;
    > + int len, ret, i;
    > + void __iomem *i2c_base;
    > + cbd_t __iomem *tbdf;
    > + cbd_t __iomem *rbdf;
    > + unsigned char brg;
    > +
    > + dev_dbg(&cpm->ofdev->dev, "cpm_i2c_setup()\n");
    > +
    > + init_waitqueue_head(&cpm->i2c_wait);
    > +
    > + cpm->irq = of_irq_to_resource(ofdev->node, 0, NULL);
    > + if (cpm->irq == NO_IRQ)
    > + return -EINVAL;
    > +
    > + /* Install interrupt handler. */
    > + ret = request_irq(cpm->irq, cpm_i2c_interrupt, 0, "cpm_i2c",
    > + &cpm->adap);
    > + if (ret)
    > + return ret;
    > +
    > + /* I2C parameter RAM */
    > + i2c_base = of_iomap(ofdev->node, 1);
    > + if (i2c_base == NULL) {
    > + ret = -EINVAL;
    > + goto out_irq;
    > + }
    > +
    > + if (of_device_is_compatible(ofdev->node, "fsl,cpm1-i2c")) {
    > +
    > + /* Check for and use a microcode relocation patch. */
    > + cpm->i2c_ram = i2c_base;
    > + cpm->i2c_addr = in_be16(&cpm->i2c_ram->rpbase);
    > +
    > + /*
    > + * Maybe should use cpm_muram_alloc instead of hardcoding
    > + * this in micropatch.c
    > + */
    > + if (cpm->i2c_addr) {
    > + cpm->i2c_ram = cpm_muram_addr(cpm->i2c_addr);
    > + iounmap(i2c_base);
    > + }
    > +
    > + cpm->version = 1;
    > +
    > + } else if (of_device_is_compatible(ofdev->node, "fsl,cpm2-i2c")) {
    > + cpm->i2c_addr = cpm_muram_alloc(sizeof(struct i2c_ram), 64);
    > + cpm->i2c_ram = cpm_muram_addr(cpm->i2c_addr);
    > + out_be16(i2c_base, cpm->i2c_addr);
    > + iounmap(i2c_base);
    > +
    > + cpm->version = 2;
    > +
    > + } else {
    > + iounmap(i2c_base);
    > + ret = -EINVAL;
    > + goto out_irq;
    > + }
    > +
    > + /* I2C control/status registers */
    > + cpm->i2c_reg = of_iomap(ofdev->node, 0);
    > + if (cpm->i2c_reg == NULL) {
    > + ret = -EINVAL;
    > + goto out_ram;
    > + }
    > +
    > + data = of_get_property(ofdev->node, "fsl,cpm-command", &len);
    > + if (!data || len != 4) {
    > + ret = -EINVAL;
    > + goto out_reg;
    > + }
    > + cpm->cp_command = *data;
    > +
    > + data = of_get_property(ofdev->node, "linux,i2c-class", &len);
    > + if (data && len == 4)
    > + cpm->adap.class = *data;
    > +
    > + data = of_get_property(ofdev->node, "bus-frequency", &len);
    > + if (data && len == 4)
    > + cpm->freq = *data;
    > + else
    > + cpm->freq = 60000; /* use 60kHz i2c bus frequency by default */
    > +
    > + /*
    > + * Allocate space for CPM_MAXBD transmit and receive buffer
    > + * descriptors in the DP ram.
    > + */
    > + cpm->dp_addr = cpm_muram_alloc(sizeof(cbd_t) * 2 * CPM_MAXBD, 8);
    > + if (!cpm->dp_addr) {
    > + ret = -ENOMEM;
    > + goto out_reg;
    > + }
    > +
    > + cpm->tbase = cpm_muram_addr(cpm->dp_addr);
    > + cpm->rbase = cpm_muram_addr(cpm->dp_addr + sizeof(cbd_t) * CPM_MAXBD);
    > +
    > + /* Allocate TX and RX buffers */
    > +
    > + tbdf = cpm->tbase;
    > + rbdf = cpm->rbase;
    > +
    > + for (i = 0; i < CPM_MAXBD; i++) {
    > + cpm->rxbuf[i] = dma_alloc_coherent(
    > + NULL, CPM_MAX_READ + 1, &cpm->rxdma[i], GFP_KERNEL);
    > + if (!cpm->rxbuf[i]) {
    > + ret = -ENOMEM;
    > + goto out_muram;
    > + }
    > + out_be32(&rbdf[i].cbd_bufaddr, ((cpm->rxdma[i] + 1) & ~1));
    > +
    > + cpm->txbuf[i] = (unsigned char *)dma_alloc_coherent(
    > + NULL, CPM_MAX_READ + 1, &cpm->txdma[i], GFP_KERNEL);
    > + if (!cpm->txbuf[i]) {
    > + ret = -ENOMEM;
    > + goto out_muram;
    > + }
    > + out_be32(&tbdf[i].cbd_bufaddr, cpm->txdma[i]);
    > + }
    > +
    > + /* Initialize Tx/Rx parameters. */
    > +
    > + cpm_reset_i2c_params(cpm);
    > +
    > + dev_dbg(&cpm->ofdev->dev, "i2c_ram %p, i2c_addr 0x%04x\n",
    > + cpm->i2c_ram, cpm->i2c_addr);
    Maybe add the i2c-bus-frequency here?

    > + dev_dbg(&cpm->ofdev->dev, "tbase 0x%04x, rbase 0x%04x\n",
    > + (u8 __iomem *)cpm->tbase - DPRAM_BASE,
    > + (u8 __iomem *)cpm->rbase - DPRAM_BASE);
    > +
    > + cpm_command(cpm->cp_command, CPM_CR_INIT_TRX);
    > +
    > + /*
    > + * Select an invalid address. Just make sure we don't use loopback mode
    > + */
    > + out_8(&cpm->i2c_reg->i2add, 0x7f << 1);
    > +
    > + /*
    > + * PDIV is set to 00 in i2mod, so brgclk/32 is used as input to the
    > + * i2c baud rate generator. This is devided by 2 x (DIV + 3) to get
    Typo. "divided"

    > + * the actual i2c bus frequency.
    > + */
    That explanation is good and useful, me thinks.

    > + brg = get_brgfreq() / (32 * 2 * cpm->freq) - 3;
    > + out_8(&cpm->i2c_reg->i2brg, brg);
    > +
    > + out_8(&cpm->i2c_reg->i2mod, 0x00);
    > + out_8(&cpm->i2c_reg->i2com, I2COM_MASTER); /* Master mode */
    > +
    > + /* Disable interrupts. */
    > + out_8(&cpm->i2c_reg->i2cmr, 0);
    > + out_8(&cpm->i2c_reg->i2cer, 0xff);
    > +
    > + return 0;
    > +
    > +out_muram:
    > + for (i = 0; i < CPM_MAXBD; i++) {
    > + if (cpm->rxbuf[i])
    > + dma_free_coherent(NULL, CPM_MAX_READ + 1,
    > + cpm->rxbuf[i], cpm->rxdma[i]);
    > + if (cpm->txbuf[i])
    > + dma_free_coherent(NULL, CPM_MAX_READ + 1,
    > + cpm->txbuf[i], cpm->txdma[i]);
    > + }
    > + cpm_muram_free(cpm->dp_addr);
    > +out_reg:
    > + iounmap(cpm->i2c_reg);
    > +out_ram:
    > + if ((cpm->version == 1) && (!cpm->i2c_addr))
    > + iounmap(cpm->i2c_ram);
    > + if (cpm->version == 2)
    > + cpm_muram_free(cpm->i2c_addr);
    > +out_irq:
    > + free_irq(cpm->irq, &cpm->adap);
    > + return ret;
    > +}
    > +
    > +static void cpm_i2c_shutdown(struct cpm_i2c *cpm)
    > +{
    > + int i;
    > +
    > + /* Shut down I2C. */
    > + clrbits8(&cpm->i2c_reg->i2mod, I2MOD_EN);
    > +
    > + /* Disable interrupts */
    > + out_8(&cpm->i2c_reg->i2cmr, 0);
    > + out_8(&cpm->i2c_reg->i2cer, 0xff);
    > +
    > + free_irq(cpm->irq, &cpm->adap);
    > +
    > + /* Free all memory */
    > + for (i = 0; i < CPM_MAXBD; i++) {
    > + dma_free_coherent(NULL, CPM_MAX_READ + 1,
    > + cpm->rxbuf[i], cpm->rxdma[i]);
    > + dma_free_coherent(NULL, CPM_MAX_READ + 1,
    > + cpm->txbuf[i], cpm->txdma[i]);
    > + }
    > +
    > + cpm_muram_free(cpm->dp_addr);
    > + iounmap(cpm->i2c_reg);
    > +
    > + if ((cpm->version == 1) && (!cpm->i2c_addr))
    > + iounmap(cpm->i2c_ram);
    > + if (cpm->version == 2)
    > + cpm_muram_free(cpm->i2c_addr);
    > +}
    > +
    > +static int __devinit cpm_i2c_probe(struct of_device *ofdev,
    > + const struct of_device_id *match)
    > +{
    > + int result, len;
    > + struct cpm_i2c *cpm;
    > + const u32 *data;
    > +
    > + cpm = kzalloc(sizeof(struct cpm_i2c), GFP_KERNEL);
    > + if (!cpm)
    > + return -ENOMEM;
    > +
    > + cpm->ofdev = ofdev;
    > +
    > + dev_set_drvdata(&ofdev->dev, cpm);
    > +
    > + cpm->adap = cpm_ops;
    > + i2c_set_adapdata(&cpm->adap, cpm);
    > + cpm->adap.dev.parent = &ofdev->dev;
    > +
    > + result = cpm_i2c_setup(cpm);
    > + if (result) {
    > + dev_err(&ofdev->dev, "Unable to init hardware\n");
    > + goto out_free;
    > + }
    > +
    > + /* register new adapter to i2c module... */
    > +
    > + data = of_get_property(ofdev->node, "linux,i2c-index", &len);
    > + if (data && len == 4) {
    > + cpm->adap.nr = *data;
    > + result = i2c_add_numbered_adapter(&cpm->adap);
    > + } else
    > + result = i2c_add_adapter(&cpm->adap);
    > +
    > + if (result < 0) {
    > + dev_err(&ofdev->dev, "Unable to register with I2C\n");
    > + goto out_shut;
    > + }
    > +
    > + dev_dbg(&ofdev->dev, "hw routines for %s registered.\n",
    > + cpm->adap.name);
    > +
    > + /*
    > + * register OF I2C devices
    > + */
    > + of_register_i2c_devices(&cpm->adap, ofdev->node);
    > +
    > + return 0;
    > +out_shut:
    > + cpm_i2c_shutdown(cpm);
    > +out_free:
    > + dev_set_drvdata(&ofdev->dev, NULL);
    > + kfree(cpm);
    > +
    > + return result;
    > +}
    > +
    > +static int __devexit cpm_i2c_remove(struct of_device *ofdev)
    > +{
    > + struct cpm_i2c *cpm = dev_get_drvdata(&ofdev->dev);
    > +
    > + i2c_del_adapter(&cpm->adap);
    > +
    > + cpm_i2c_shutdown(cpm);
    > +
    > + dev_set_drvdata(&ofdev->dev, NULL);
    > + kfree(cpm);
    > +
    > + return 0;
    > +}
    > +
    > +static const struct of_device_id cpm_i2c_match[] = {
    > + {
    > + .compatible = "fsl,cpm1-i2c",
    > + },
    > + {
    > + .compatible = "fsl,cpm2-i2c",
    > + },
    > + {},
    > +};
    > +
    > +MODULE_DEVICE_TABLE(of, cpm_i2c_match);
    > +
    > +static struct of_platform_driver cpm_i2c_driver = {
    > + .match_table = cpm_i2c_match,
    > + .probe = cpm_i2c_probe,
    > + .remove = __devexit_p(cpm_i2c_remove),
    > + .driver = {
    > + .name = "fsl-i2c-cpm",
    > + .owner = THIS_MODULE,
    > + }
    > +};
    > +
    > +static int __init cpm_i2c_init(void)
    > +{
    > + return of_register_platform_driver(&cpm_i2c_driver);
    > +}
    > +
    > +static void __exit cpm_i2c_exit(void)
    > +{
    > + of_unregister_platform_driver(&cpm_i2c_driver);
    > +}
    > +
    > +module_init(cpm_i2c_init);
    > +module_exit(cpm_i2c_exit);
    > +
    > +MODULE_AUTHOR("Jochen Friedrich <jochen@scram.de>");
    > +MODULE_DESCRIPTION("I2C-Bus adapter routines for CPM boards");
    > +MODULE_LICENSE("GPL");
    > --
    > 1.5.5.1
    >

    All the best,

    Wolfram

    --
    Dipl.-Ing. Wolfram Sang | http://www.pengutronix.de
    Pengutronix - Linux Solutions for Science and Industry
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