[PATCH] [ARM] tegra: Add i2c support

Mike Rapoport mike.rapoport at gmail.com
Fri Jul 30 16:44:07 EDT 2010


Hi Colin,

On Fri, Jul 30, 2010 at 3:36 AM, Colin Cross <ccross at google.com> wrote:
> From: Colin Cross <ccross at android.com>
>
> CC: linux-i2c at vger.kernel.org
> Signed-off-by: Colin Cross <ccross at android.com>
> ---
>  drivers/i2c/busses/Kconfig     |    7 +
>  drivers/i2c/busses/Makefile    |    1 +
>  drivers/i2c/busses/i2c-tegra.c |  665 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/i2c-tegra.h      |   25 ++
>  4 files changed, 698 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/i2c/busses/i2c-tegra.c
>  create mode 100644 include/linux/i2c-tegra.h
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index bceafbf..a4dbfdb 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -582,6 +582,13 @@ config I2C_STU300
>          This driver can also be built as a module. If so, the module
>          will be called i2c-stu300.
>
> +config I2C_TEGRA
> +       tristate "NVIDIA Tegra internal I2C controller"
> +       depends on ARCH_TEGRA
> +       help
> +         If you say yes to this option, support will be included for the
> +         I2C controller embedded in NVIDIA Tegra SOCs
> +
>  config I2C_VERSATILE
>        tristate "ARM Versatile/Realview I2C bus support"
>        depends on ARCH_VERSATILE || ARCH_REALVIEW || ARCH_VEXPRESS
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 936880b..0d401c4 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -56,6 +56,7 @@ obj-$(CONFIG_I2C_SH7760)      += i2c-sh7760.o
>  obj-$(CONFIG_I2C_SH_MOBILE)    += i2c-sh_mobile.o
>  obj-$(CONFIG_I2C_SIMTEC)       += i2c-simtec.o
>  obj-$(CONFIG_I2C_STU300)       += i2c-stu300.o
> +obj-$(CONFIG_I2C_TEGRA)                += i2c-tegra.o
>  obj-$(CONFIG_I2C_VERSATILE)    += i2c-versatile.o
>  obj-$(CONFIG_I2C_OCTEON)       += i2c-octeon.o
>  obj-$(CONFIG_I2C_XILINX)       += i2c-xiic.o
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> new file mode 100644
> index 0000000..ee8a7aa
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -0,0 +1,665 @@
> +/*
> + * drivers/i2c/busses/i2c-tegra.c
> + *
> + * Copyright (C) 2010 Google, Inc.
> + * Author: Colin Cross <ccross at android.com>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * 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.
> + *
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/platform_device.h>
> +#include <linux/clk.h>
> +#include <linux/i2c.h>
> +#include <linux/io.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/slab.h>
> +#include <linux/i2c-tegra.h>
> +
> +#include <asm/unaligned.h>
> +
> +#include <mach/clk.h>
> +
> +#define TEGRA_I2C_TIMEOUT (msecs_to_jiffies(1000))
> +#define BYTES_PER_FIFO_WORD 4
> +
> +#define I2C_CNFG                               0x000
> +#define I2C_CNFG_PACKET_MODE_EN                        (1<<10)
> +#define I2C_CNFG_NEW_MASTER_FSM                        (1<<11)
> +#define I2C_SL_CNFG                            0x020
> +#define I2C_SL_CNFG_NEWSL                      (1<<2)
> +#define I2C_SL_ADDR1                           0x02c
> +#define I2C_TX_FIFO                            0x050
> +#define I2C_RX_FIFO                            0x054
> +#define I2C_PACKET_TRANSFER_STATUS             0x058
> +#define I2C_FIFO_CONTROL                       0x05c
> +#define I2C_FIFO_CONTROL_TX_FLUSH              (1<<1)
> +#define I2C_FIFO_CONTROL_RX_FLUSH              (1<<0)
> +#define I2C_FIFO_CONTROL_TX_TRIG_SHIFT         5
> +#define I2C_FIFO_CONTROL_RX_TRIG_SHIFT         2
> +#define I2C_FIFO_STATUS                                0x060
> +#define I2C_FIFO_STATUS_TX_MASK                        0xF0
> +#define I2C_FIFO_STATUS_TX_SHIFT               4
> +#define I2C_FIFO_STATUS_RX_MASK                        0x0F
> +#define I2C_FIFO_STATUS_RX_SHIFT               0
> +#define I2C_INT_MASK                           0x064
> +#define I2C_INT_STATUS                         0x068
> +#define I2C_INT_PACKET_XFER_COMPLETE           (1<<7)
> +#define I2C_INT_ALL_PACKETS_XFER_COMPLETE      (1<<6)
> +#define I2C_INT_TX_FIFO_OVERFLOW               (1<<5)
> +#define I2C_INT_RX_FIFO_UNDERFLOW              (1<<4)
> +#define I2C_INT_NO_ACK                         (1<<3)
> +#define I2C_INT_ARBITRATION_LOST               (1<<2)
> +#define I2C_INT_TX_FIFO_DATA_REQ               (1<<1)
> +#define I2C_INT_RX_FIFO_DATA_REQ               (1<<0)
> +#define I2C_CLK_DIVISOR                                0x06c
> +
> +#define DVC_CTRL_REG1                          0x000
> +#define DVC_CTRL_REG1_INTR_EN                  (1<<10)
> +#define DVC_CTRL_REG2                          0x004
> +#define DVC_CTRL_REG3                          0x008
> +#define DVC_CTRL_REG3_SW_PROG                  (1<<26)
> +#define DVC_CTRL_REG3_I2C_DONE_INTR_EN         (1<<30)
> +#define DVC_STATUS                             0x00c
> +#define DVC_STATUS_I2C_DONE_INTR               (1<<30)
> +
> +#define I2C_ERR_NONE                           0x00
> +#define I2C_ERR_NO_ACK                         0x01
> +#define I2C_ERR_ARBITRATION_LOST               0x02
> +
> +#define PACKET_HEADER0_HEADER_SIZE_SHIFT       28
> +#define PACKET_HEADER0_PACKET_ID_SHIFT         16
> +#define PACKET_HEADER0_CONT_ID_SHIFT           12
> +#define PACKET_HEADER0_PROTOCOL_I2C            (1<<4)
> +
> +#define I2C_HEADER_HIGHSPEED_MODE              (1<<22)
> +#define I2C_HEADER_CONT_ON_NAK                 (1<<21)
> +#define I2C_HEADER_SEND_START_BYTE             (1<<20)
> +#define I2C_HEADER_READ                                (1<<19)
> +#define I2C_HEADER_10BIT_ADDR                  (1<<18)
> +#define I2C_HEADER_IE_ENABLE                   (1<<17)
> +#define I2C_HEADER_REPEAT_START                        (1<<16)
> +#define I2C_HEADER_MASTER_ADDR_SHIFT           12
> +#define I2C_HEADER_SLAVE_ADDR_SHIFT            1
> +
> +struct tegra_i2c_dev {
> +       struct device *dev;
> +       struct i2c_adapter adapter;
> +       struct clk *clk;
> +       struct clk *i2c_clk;
> +       struct resource *iomem;
> +       void __iomem *base;
> +       int cont_id;
> +       int irq;
> +       int is_dvc;
> +       struct completion msg_complete;
> +       int msg_err;
> +       u8 *msg_buf;
> +       size_t msg_buf_remaining;
> +       int msg_read;
> +       int msg_transfer_complete;
> +       unsigned long bus_clk_rate;
> +       bool is_suspended;
> +};
> +
> +static void dvc_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned long reg)
> +{
> +       writel(val, i2c_dev->base + reg);
> +}
> +
> +static u32 dvc_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
> +{
> +       return readl(i2c_dev->base + reg);
> +}
> +
> +/* i2c_writel and i2c_readl will offset the register if necessary to talk
> + * to the I2C block inside the DVC block
> + */
> +static void i2c_writel(struct tegra_i2c_dev *i2c_dev, u32 val, unsigned long reg)
> +{
> +       if (i2c_dev->is_dvc)
> +               reg += (reg >= I2C_TX_FIFO) ? 0x10 : 0x40;
> +       writel(val, i2c_dev->base + reg);
> +}
> +
> +static u32 i2c_readl(struct tegra_i2c_dev *i2c_dev, unsigned long reg)
> +{
> +       if (i2c_dev->is_dvc)
> +               reg += (reg >= I2C_TX_FIFO) ? 0x10 : 0x40;
> +       return readl(i2c_dev->base + reg);
> +}
> +
> +static void tegra_i2c_mask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
> +{
> +       u32 int_mask = i2c_readl(i2c_dev, I2C_INT_MASK);
> +       int_mask &= ~mask;
> +       i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
> +}
> +
> +static void tegra_i2c_unmask_irq(struct tegra_i2c_dev *i2c_dev, u32 mask)
> +{
> +       u32 int_mask = i2c_readl(i2c_dev, I2C_INT_MASK);
> +       int_mask |= mask;
> +       i2c_writel(i2c_dev, int_mask, I2C_INT_MASK);
> +}
> +
> +static void tegra_i2c_set_clk(struct tegra_i2c_dev *i2c_dev, unsigned int freq)
> +{
> +       clk_set_rate(i2c_dev->clk, freq * 8);
> +}
> +
> +static int tegra_i2c_flush_fifos(struct tegra_i2c_dev *i2c_dev)
> +{
> +       unsigned long timeout = jiffies + HZ;
> +       u32 val = i2c_readl(i2c_dev, I2C_FIFO_CONTROL);
> +       val |= I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH;
> +       i2c_writel(i2c_dev, val, I2C_FIFO_CONTROL);
> +
> +       while (i2c_readl(i2c_dev, I2C_FIFO_CONTROL) &
> +               (I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH)) {
> +               if (time_after(jiffies, timeout)) {
> +                       dev_warn(i2c_dev->dev, "timeout waiting for fifo flush\n");
> +                       return -ETIMEDOUT;
> +               }
> +               msleep(1);
> +       }
> +       return 0;
> +}
> +
> +static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev *i2c_dev)
> +{
> +       u32 val;
> +       int rx_fifo_avail;
> +       int word;
> +       u8 *buf = i2c_dev->msg_buf;
> +       size_t buf_remaining = i2c_dev->msg_buf_remaining;
> +       int words_to_transfer;
> +
> +       val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
> +       rx_fifo_avail = (val & I2C_FIFO_STATUS_RX_MASK) >>
> +               I2C_FIFO_STATUS_RX_SHIFT;
> +
> +       words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
> +       if (words_to_transfer > rx_fifo_avail)
> +               words_to_transfer = rx_fifo_avail;
> +
> +       for (word = 0; word < words_to_transfer; word++) {
> +               val = i2c_readl(i2c_dev, I2C_RX_FIFO);
> +               put_unaligned_le32(val, buf);
> +               buf += BYTES_PER_FIFO_WORD;
> +               buf_remaining -= BYTES_PER_FIFO_WORD;
> +               rx_fifo_avail--;
> +       }
> +
> +       if (rx_fifo_avail > 0 && buf_remaining > 0) {
> +               int bytes_to_transfer = buf_remaining;
> +               int byte;
> +               BUG_ON(bytes_to_transfer > 3);
> +               val = i2c_readl(i2c_dev, I2C_RX_FIFO);
> +               for (byte = 0; byte < bytes_to_transfer; byte++) {
> +                       *buf++ = val & 0xFF;
> +                       val >>= 8;
> +               }
> +               buf_remaining -= bytes_to_transfer;
> +               rx_fifo_avail--;
> +       }
> +       BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
> +       i2c_dev->msg_buf_remaining = buf_remaining;
> +       i2c_dev->msg_buf = buf;
> +       return 0;
> +}
> +
> +static int tegra_i2c_fill_tx_fifo(struct tegra_i2c_dev *i2c_dev)
> +{
> +       u32 val;
> +       int tx_fifo_avail;
> +       int word;
> +       u8 *buf = i2c_dev->msg_buf;
> +       size_t buf_remaining = i2c_dev->msg_buf_remaining;
> +       int words_to_transfer;
> +
> +       val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
> +       tx_fifo_avail = (val & I2C_FIFO_STATUS_TX_MASK) >>
> +               I2C_FIFO_STATUS_TX_SHIFT;
> +
> +       words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
> +       if (words_to_transfer > tx_fifo_avail)
> +               words_to_transfer = tx_fifo_avail;
> +
> +       for (word = 0; word < words_to_transfer; word++) {
> +               val = get_unaligned_le32(buf);
> +               i2c_writel(i2c_dev, val, I2C_TX_FIFO);
> +               buf += BYTES_PER_FIFO_WORD;
> +               buf_remaining -= BYTES_PER_FIFO_WORD;
> +               tx_fifo_avail--;
> +       }
> +
> +       if (tx_fifo_avail > 0 && buf_remaining > 0) {
> +               int bytes_to_transfer = buf_remaining;
> +               int byte;
> +               BUG_ON(bytes_to_transfer > 3);
> +               val = 0;
> +               for (byte = 0; byte < bytes_to_transfer; byte++)
> +                       val |= (*buf++) << (byte * 8);
> +               i2c_writel(i2c_dev, val, I2C_TX_FIFO);
> +               buf_remaining -= bytes_to_transfer;
> +               tx_fifo_avail--;
> +       }
> +       BUG_ON(tx_fifo_avail > 0 && buf_remaining > 0);
> +       i2c_dev->msg_buf_remaining = buf_remaining;
> +       i2c_dev->msg_buf = buf;
> +       return 0;
> +}
> +
> +/* One of the Tegra I2C blocks is inside the DVC (Digital Voltage Controller)
> + * block.  This block is identical to the rest of the I2C blocks, except that
> + * it only supports master mode, it has registers moved around, and it needs
> + * some extra init to get it into I2C mode.  The register moves are handled
> + * by i2c_readl and i2c_writel
> + */
> +static void tegra_dvc_init(struct tegra_i2c_dev *i2c_dev)
> +{
> +       u32 val = 0;
> +       val = dvc_readl(i2c_dev, DVC_CTRL_REG3);
> +       val |= DVC_CTRL_REG3_SW_PROG;
> +       val |= DVC_CTRL_REG3_I2C_DONE_INTR_EN;
> +       dvc_writel(i2c_dev, val, DVC_CTRL_REG3);
> +
> +       val = dvc_readl(i2c_dev, DVC_CTRL_REG1);
> +       val |= DVC_CTRL_REG1_INTR_EN;
> +       dvc_writel(i2c_dev, val, DVC_CTRL_REG1);
> +}
> +
> +static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
> +{
> +       u32 val;
> +       int err = 0;
> +
> +       tegra_periph_reset_assert(i2c_dev->clk);
> +       msleep(1);
> +       tegra_periph_reset_deassert(i2c_dev->clk);
> +       msleep(1);
> +
> +       clk_enable(i2c_dev->clk);
> +
> +       if (i2c_dev->is_dvc)
> +               tegra_dvc_init(i2c_dev);
> +
> +       val = I2C_CNFG_NEW_MASTER_FSM | I2C_CNFG_PACKET_MODE_EN;
> +       i2c_writel(i2c_dev, val, I2C_CNFG);
> +       i2c_writel(i2c_dev, 0, I2C_INT_MASK);
> +       tegra_i2c_set_clk(i2c_dev, i2c_dev->bus_clk_rate);
> +
> +       val = 7 << I2C_FIFO_CONTROL_TX_TRIG_SHIFT |
> +               0 << I2C_FIFO_CONTROL_RX_TRIG_SHIFT;
> +       i2c_writel(i2c_dev, val, I2C_FIFO_CONTROL);
> +
> +       if (tegra_i2c_flush_fifos(i2c_dev))
> +               err = -ETIMEDOUT;
> +
> +       clk_disable(i2c_dev->clk);
> +       return 0;
> +}
> +
> +static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
> +{
> +       u32 status;
> +       const u32 status_err = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
> +       struct tegra_i2c_dev *i2c_dev = dev_id;
> +
> +       status = i2c_readl(i2c_dev, I2C_INT_STATUS);
> +
> +       if (status == 0) {
> +               dev_warn(i2c_dev->dev, "irq status 0 %08x\n",
> +                       i2c_readl(i2c_dev, I2C_PACKET_TRANSFER_STATUS));
> +               return IRQ_HANDLED;
> +       }
> +
> +       if (unlikely(status & status_err)) {
> +               if (status & I2C_INT_NO_ACK)
> +                       i2c_dev->msg_err |= I2C_ERR_NO_ACK;
> +               if (status & I2C_INT_ARBITRATION_LOST)
> +                       i2c_dev->msg_err |= I2C_ERR_ARBITRATION_LOST;
> +               complete(&i2c_dev->msg_complete);
> +               goto err;
> +       }
> +
> +       if (i2c_dev->msg_read && (status & I2C_INT_RX_FIFO_DATA_REQ)) {
> +               if (i2c_dev->msg_buf_remaining)
> +                       tegra_i2c_empty_rx_fifo(i2c_dev);
> +               else
> +                       BUG();
> +       }
> +
> +       if (!i2c_dev->msg_read && (status & I2C_INT_TX_FIFO_DATA_REQ)) {
> +               if (i2c_dev->msg_buf_remaining)
> +                       tegra_i2c_fill_tx_fifo(i2c_dev);
> +               else
> +                       tegra_i2c_mask_irq(i2c_dev, I2C_INT_TX_FIFO_DATA_REQ);
> +       }
> +
> +       if (status & I2C_INT_PACKET_XFER_COMPLETE)
> +               i2c_dev->msg_transfer_complete = 1;
> +
> +       if (i2c_dev->msg_transfer_complete && !i2c_dev->msg_buf_remaining)
> +               complete(&i2c_dev->msg_complete);
> +       i2c_writel(i2c_dev, status, I2C_INT_STATUS);
> +       if (i2c_dev->is_dvc)
> +               dvc_writel(i2c_dev, DVC_STATUS_I2C_DONE_INTR, DVC_STATUS);
> +       return IRQ_HANDLED;
> +err:
> +       /* An error occured, mask all interrupts */
> +       tegra_i2c_mask_irq(i2c_dev, I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST |
> +               I2C_INT_PACKET_XFER_COMPLETE | I2C_INT_TX_FIFO_DATA_REQ |
> +               I2C_INT_RX_FIFO_DATA_REQ);
> +       i2c_writel(i2c_dev, status, I2C_INT_STATUS);
> +       return IRQ_HANDLED;
> +}
> +
> +static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> +       struct i2c_msg *msg, int stop)
> +{
> +       u32 packet_header;
> +       u32 int_mask;
> +       int ret;
> +
> +       tegra_i2c_flush_fifos(i2c_dev);
> +       i2c_writel(i2c_dev, 0xFF, I2C_INT_STATUS);
> +
> +       if (msg->len == 0)
> +               return -EINVAL;
> +
> +       i2c_dev->msg_buf = msg->buf;
> +       i2c_dev->msg_buf_remaining = msg->len;
> +       i2c_dev->msg_err = I2C_ERR_NONE;
> +       i2c_dev->msg_transfer_complete = 0;
> +       i2c_dev->msg_read = (msg->flags & I2C_M_RD);
> +       INIT_COMPLETION(i2c_dev->msg_complete);
> +
> +       packet_header = (0 << PACKET_HEADER0_HEADER_SIZE_SHIFT) |
> +                       PACKET_HEADER0_PROTOCOL_I2C |
> +                       (i2c_dev->cont_id << PACKET_HEADER0_CONT_ID_SHIFT) |
> +                       (1 << PACKET_HEADER0_PACKET_ID_SHIFT);
> +       i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
> +
> +       packet_header = msg->len - 1;
> +       i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
> +
> +       packet_header = msg->addr << I2C_HEADER_SLAVE_ADDR_SHIFT;
> +       packet_header |= I2C_HEADER_IE_ENABLE;
> +       if (msg->flags & I2C_M_TEN)
> +               packet_header |= I2C_HEADER_10BIT_ADDR;
> +       if (msg->flags & I2C_M_IGNORE_NAK)
> +               packet_header |= I2C_HEADER_CONT_ON_NAK;
> +       if (msg->flags & I2C_M_NOSTART)
> +               packet_header |= I2C_HEADER_REPEAT_START;
> +       if (msg->flags & I2C_M_RD)
> +               packet_header |= I2C_HEADER_READ;
> +       i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);
> +
> +       if (!(msg->flags & I2C_M_RD))
> +               tegra_i2c_fill_tx_fifo(i2c_dev);
> +
> +       int_mask = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
> +       if (msg->flags & I2C_M_RD)
> +               int_mask |= I2C_INT_RX_FIFO_DATA_REQ;
> +       else if (i2c_dev->msg_buf_remaining)
> +               int_mask |= I2C_INT_TX_FIFO_DATA_REQ;
> +       tegra_i2c_unmask_irq(i2c_dev, int_mask);
> +       pr_debug("unmasked irq: %02x\n", i2c_readl(i2c_dev, I2C_INT_MASK));
> +
> +       ret = wait_for_completion_timeout(&i2c_dev->msg_complete, TEGRA_I2C_TIMEOUT);
> +       tegra_i2c_mask_irq(i2c_dev, int_mask);
> +
> +       if (WARN_ON(ret == 0)) {
> +               dev_err(i2c_dev->dev, "i2c transfer timed out\n");
> +
> +               tegra_i2c_init(i2c_dev);
> +               return -ETIMEDOUT;
> +       }
> +
> +       pr_debug("transfer complete: %d %d %d\n", ret, completion_done(&i2c_dev->msg_complete), i2c_dev->msg_err);
> +
> +       if (likely(i2c_dev->msg_err == I2C_ERR_NONE))
> +               return 0;
> +
> +       tegra_i2c_init(i2c_dev);
> +       if (i2c_dev->msg_err == I2C_ERR_NO_ACK) {
> +               if (msg->flags & I2C_M_IGNORE_NAK)
> +                       return 0;
> +               return -EREMOTEIO;
> +       }
> +
> +       return -EIO;
> +}
> +
> +static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
> +       int num)
> +{
> +       struct tegra_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
> +       int i;
> +       int ret = 0;
> +
> +       if (i2c_dev->is_suspended)
> +               return -EBUSY;
> +
> +       clk_enable(i2c_dev->clk);
> +       for (i = 0; i < num; i++) {
> +               int stop = (i == (num - 1)) ? 1  : 0;
> +               ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], stop);
> +               if (ret)
> +                       break;
> +       }
> +       clk_disable(i2c_dev->clk);
> +       return i;

In case of error the i2c_transfer should return the error code, so the
return statement should be
       return ret ?: i;

> +}
> +
> +static u32 tegra_i2c_func(struct i2c_adapter *adap)
> +{
> +       /* FIXME: For now keep it simple and don't support protocol mangling
> +          features */
> +       return I2C_FUNC_I2C;
> +}
> +
> +static const struct i2c_algorithm tegra_i2c_algo = {
> +       .master_xfer    = tegra_i2c_xfer,
> +       .functionality  = tegra_i2c_func,
> +};
> +
> +static int tegra_i2c_probe(struct platform_device *pdev)
> +{
> +       struct tegra_i2c_dev *i2c_dev;
> +       struct tegra_i2c_platform_data *pdata = pdev->dev.platform_data;
> +       struct resource *res;
> +       struct resource *iomem;
> +       struct clk *clk;
> +       struct clk *i2c_clk;
> +       void *base;
> +       int irq;
> +       int ret = 0;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "no mem resource?\n");
> +               return -ENODEV;
> +       }
> +       iomem = request_mem_region(res->start, resource_size(res), pdev->name);
> +       if (!iomem) {
> +               dev_err(&pdev->dev, "I2C region already claimed\n");
> +               return -EBUSY;
> +       }
> +
> +       base = ioremap(iomem->start, resource_size(iomem));
> +       if (!base) {
> +               dev_err(&pdev->dev, "Can't ioremap I2C region\n");
> +               return -ENOMEM;
> +       }
> +
> +       res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
> +       if (!res) {
> +               dev_err(&pdev->dev, "no irq resource?\n");
> +               ret = -ENODEV;
> +               goto err_iounmap;
> +       }
> +       irq = res->start;
> +
> +       clk = clk_get(&pdev->dev, NULL);
> +       if (!clk) {
> +               ret = -ENOMEM;
> +               goto err_release_region;
> +       }
> +
> +       i2c_clk = clk_get(&pdev->dev, "i2c");
> +       if (!i2c_clk) {
> +               ret = -ENOMEM;
> +               goto err_clk_put;
> +       }
> +
> +       i2c_dev = kzalloc(sizeof(struct tegra_i2c_dev), GFP_KERNEL);
> +       if (!i2c_dev) {
> +               ret = -ENOMEM;
> +               goto err_i2c_clk_put;
> +       }
> +
> +       i2c_dev->base = base;
> +       i2c_dev->clk = clk;
> +       i2c_dev->i2c_clk = i2c_clk;
> +       i2c_dev->iomem = iomem;
> +       i2c_dev->adapter.algo = &tegra_i2c_algo;
> +       i2c_dev->irq = irq;
> +       i2c_dev->cont_id = pdev->id;
> +       i2c_dev->dev = &pdev->dev;
> +       i2c_dev->bus_clk_rate = pdata ? pdata->bus_clk_rate : 100000;
> +
> +       if (pdev->id == 3)
> +               i2c_dev->is_dvc = 1;
> +       init_completion(&i2c_dev->msg_complete);
> +
> +       platform_set_drvdata(pdev, i2c_dev);
> +
> +       ret = tegra_i2c_init(i2c_dev);
> +       if (ret)
> +               goto err_free;
> +
> +       ret = request_irq(i2c_dev->irq, tegra_i2c_isr, IRQF_DISABLED,
> +               pdev->name, i2c_dev);
> +       if (ret) {
> +               dev_err(&pdev->dev, "Failed to request irq %i\n", i2c_dev->irq);
> +               goto err_free;
> +       }
> +
> +       clk_enable(i2c_dev->i2c_clk);
> +
> +       i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
> +       i2c_dev->adapter.owner = THIS_MODULE;
> +       i2c_dev->adapter.class = I2C_CLASS_HWMON;
> +       strlcpy(i2c_dev->adapter.name, "Tegra I2C adapter",
> +               sizeof(i2c_dev->adapter.name));
> +       i2c_dev->adapter.algo = &tegra_i2c_algo;
> +       i2c_dev->adapter.dev.parent = &pdev->dev;
> +       i2c_dev->adapter.nr = pdev->id;
> +
> +       ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
> +       if (ret) {
> +               dev_err(&pdev->dev, "Failed to add I2C adapter\n");
> +               goto err_free_irq;
> +       }
> +
> +       return 0;
> +err_free_irq:
> +       free_irq(i2c_dev->irq, i2c_dev);
> +err_free:
> +       kfree(i2c_dev);
> +err_i2c_clk_put:
> +       clk_put(i2c_clk);
> +err_clk_put:
> +       clk_put(clk);
> +err_release_region:
> +       release_mem_region(iomem->start, resource_size(iomem));
> +err_iounmap:
> +       iounmap(base);
> +       return ret;
> +}
> +
> +static int tegra_i2c_remove(struct platform_device *pdev)
> +{
> +       struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +       i2c_del_adapter(&i2c_dev->adapter);
> +       free_irq(i2c_dev->irq, i2c_dev);
> +       clk_put(i2c_dev->i2c_clk);
> +       clk_put(i2c_dev->clk);
> +       release_mem_region(i2c_dev->iomem->start,
> +               resource_size(i2c_dev->iomem));
> +       iounmap(i2c_dev->base);
> +       kfree(i2c_dev);
> +       return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int tegra_i2c_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> +       struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +
> +       i2c_lock_adapter(&i2c_dev->adapter);
> +       i2c_dev->is_suspended = true;
> +       i2c_unlock_adapter(&i2c_dev->adapter);
> +
> +       return 0;
> +}
> +
> +static int tegra_i2c_resume(struct platform_device *pdev)
> +{
> +       struct tegra_i2c_dev *i2c_dev = platform_get_drvdata(pdev);
> +       int ret;
> +
> +       i2c_lock_adapter(&i2c_dev->adapter);
> +
> +       ret = tegra_i2c_init(i2c_dev);
> +
> +       if (ret) {
> +               i2c_unlock_adapter(&i2c_dev->adapter);
> +               return ret;
> +       }
> +
> +       i2c_dev->is_suspended = false;
> +
> +       i2c_unlock_adapter(&i2c_dev->adapter);
> +
> +       return 0;
> +}
> +#endif
> +
> +static struct platform_driver tegra_i2c_driver = {
> +       .probe   = tegra_i2c_probe,
> +       .remove  = tegra_i2c_remove,
> +#ifdef CONFIG_PM
> +       .suspend = tegra_i2c_suspend,
> +       .resume  = tegra_i2c_resume,
> +#endif
> +       .driver  = {
> +               .name  = "tegra-i2c",
> +               .owner = THIS_MODULE,
> +       },
> +};
> +
> +static int __init tegra_i2c_init_driver(void)
> +{
> +       return platform_driver_register(&tegra_i2c_driver);
> +}
> +module_init(tegra_i2c_init_driver);
> +
> +static void __exit tegra_i2c_exit_driver(void)
> +{
> +       platform_driver_unregister(&tegra_i2c_driver);
> +}
> +module_exit(tegra_i2c_exit_driver);
> diff --git a/include/linux/i2c-tegra.h b/include/linux/i2c-tegra.h
> new file mode 100644
> index 0000000..9c85da4
> --- /dev/null
> +++ b/include/linux/i2c-tegra.h
> @@ -0,0 +1,25 @@
> +/*
> + * drivers/i2c/busses/i2c-tegra.c
> + *
> + * Copyright (C) 2010 Google, Inc.
> + * Author: Colin Cross <ccross at android.com>
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * 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.
> + *
> + */
> +
> +#ifndef _LINUX_I2C_TEGRA_H
> +#define _LINUX_I2C_TEGRA_H
> +
> +struct tegra_i2c_platform_data {
> +       unsigned long bus_clk_rate;
> +};
> +
> +#endif /* _LINUX_I2C_TEGRA_H */
> --
> 1.7.1
>
>
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>



-- 
    Sincerely Yours,
        Mike.



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