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Message-ID: <CAHuqX+GjysHvd7b8n5vjBHA+HNOY6aeRaKSnH0Jq-0z_vni9Hg@mail.gmail.com>
Date: Tue, 4 Dec 2012 07:53:57 +0900
From: Giridhar Maruthy <giridhar.maruthy@...aro.org>
To: Kyungmin Park <kmpark@...radead.org>
Cc: linux-arm-kernel@...ts.infradead.org,
linux-samsung-soc@...r.kernel.org, linux-i2c@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] I2C: EXYNOS: Add slave support to i2c
Thank you Kyungmin Park for the review.
On 3 December 2012 22:28, Kyungmin Park <kmpark@...radead.org> wrote:
>
> Hi,
>
> On Mon, Dec 3, 2012 at 9:16 PM, Giridhar Maruthy
> <giridhar.maruthy@...aro.org> wrote:
> > This patch adds slave support to i2c. The dt entry i2c-mode
> > decides at probe time if the controller needs to work in
> > slave mode and the controller is accordingly programmed.
> >
> > Signed-off-by: Giridhar Maruthy <giridhar.maruthy@...aro.org>
> > ---
> > drivers/i2c/busses/i2c-s3c2410.c | 100
> > ++++++++++++++++++++++++++------------
> > 1 file changed, 68 insertions(+), 32 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-s3c2410.c
> > b/drivers/i2c/busses/i2c-s3c2410.c
> > index e93e7d6..d83a6d7 100644
> > --- a/drivers/i2c/busses/i2c-s3c2410.c
> > +++ b/drivers/i2c/busses/i2c-s3c2410.c
> > @@ -53,6 +53,9 @@
> > /* Max time to wait for bus to become idle after a xfer (in us) */
> > #define S3C2410_IDLE_TIMEOUT 5000
> >
> > +/* To find the master/slave mode of current controller */
> > +#define is_master(i2c) (!i2c->i2c_mode)
> > +
> > /* i2c controller state */
> > enum s3c24xx_i2c_state {
> > STATE_IDLE,
> > @@ -89,6 +92,8 @@ struct s3c24xx_i2c {
> > #ifdef CONFIG_CPU_FREQ
> > struct notifier_block freq_transition;
> > #endif
> > + /* i2c_mode: 0 is for master; and 1 is for slave */
> > + unsigned int i2c_mode;
> If it's used for master or not, doesn't better to use 'is_master' or
> 'is_slave'? what's the meaning of 'i2c_mode'?
> and
> #define is_master(i2c) (i2c->is_master)
I thought mode indicates master mode or slave mode, but I agree
'is_master' name is better. Will change that.
>
> Thank you,
> Kyungmin Park
> > };
> >
> > static struct platform_device_id s3c24xx_driver_ids[] = {
> > @@ -202,11 +207,21 @@ static void s3c24xx_i2c_message_start(struct
> > s3c24xx_i2c *i2c,
> > stat = 0;
> > stat |= S3C2410_IICSTAT_TXRXEN;
> >
> > - if (msg->flags & I2C_M_RD) {
> > - stat |= S3C2410_IICSTAT_MASTER_RX;
> > - addr |= 1;
> > - } else
> > - stat |= S3C2410_IICSTAT_MASTER_TX;
> > + if (is_master(i2c)) {
> > + /* Master mode */
> > + if (msg->flags & I2C_M_RD) {
> > + stat |= S3C2410_IICSTAT_MASTER_RX;
> > + addr |= 1;
> > + } else
> > + stat |= S3C2410_IICSTAT_MASTER_TX;
> > + } else {
> > + /* Slave mode */
> > + if (msg->flags & I2C_M_RD) {
> > + stat |= S3C2410_IICSTAT_SLAVE_RX;
> > + addr |= 1;
> > + } else
> > + stat |= S3C2410_IICSTAT_SLAVE_TX;
> > + }
> >
> > if (msg->flags & I2C_M_REV_DIR_ADDR)
> > addr ^= 1;
> > @@ -228,8 +243,10 @@ static void s3c24xx_i2c_message_start(struct
> > s3c24xx_i2c *i2c,
> > dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
> > writel(iiccon, i2c->regs + S3C2410_IICCON);
> >
> > - stat |= S3C2410_IICSTAT_START;
> > - writel(stat, i2c->regs + S3C2410_IICSTAT);
> > + if (is_master(i2c)) {
> > + stat |= S3C2410_IICSTAT_START;
> > + writel(stat, i2c->regs + S3C2410_IICSTAT);
> > + }
> > }
> >
> > static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
> > @@ -272,14 +289,19 @@ static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c
> > *i2c, int ret)
> > * devices, the host as Master and the HDMIPHY device as the slave.
> > * Skipping the STOP condition has been tested on this bus and
> > works.
> > */
> > - if (i2c->quirks & QUIRK_HDMIPHY) {
> > - /* Stop driving the I2C pins */
> > - iicstat &= ~S3C2410_IICSTAT_TXRXEN;
> > - } else {
> > - /* stop the transfer */
> > - iicstat &= ~S3C2410_IICSTAT_START;
> > + if (is_master(i2c)) {
> > + if (i2c->quirks & QUIRK_HDMIPHY) {
> > + /* Stop driving the I2C pins */
> > + iicstat &= ~S3C2410_IICSTAT_TXRXEN;
> > + } else {
> > + /* stop the transfer */
> > + if (is_master(i2c)) {
> > + /* Start/Stop required only for master */
> > + iicstat &= ~S3C2410_IICSTAT_START;
> > + }
> > + }
> > + writel(iicstat, i2c->regs + S3C2410_IICSTAT);
> > }
> > - writel(iicstat, i2c->regs + S3C2410_IICSTAT);
> >
> > i2c->state = STATE_STOP;
> >
> > @@ -348,7 +370,8 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c,
> > unsigned long iicstat)
> > */
> >
> > if (iicstat & S3C2410_IICSTAT_LASTBIT &&
> > - !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
> > + !(i2c->msg->flags & I2C_M_IGNORE_NAK) &&
> > + is_master(i2c)) {
> > /* ack was not received... */
> >
> > dev_dbg(i2c->dev, "ack was not received\n");
> > @@ -380,7 +403,7 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c,
> > unsigned long iicstat)
> > * end of the message, and if so, work out what to do
> > */
> >
> > - if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
> > + if (!(i2c->msg->flags & I2C_M_IGNORE_NAK) && is_master(i2c))
> > {
> > if (iicstat & S3C2410_IICSTAT_LASTBIT) {
> > dev_dbg(i2c->dev, "WRITE: No Ack\n");
> >
> > @@ -432,7 +455,6 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c,
> > unsigned long iicstat)
> >
> > } else {
> > /* send stop */
> > -
> > s3c24xx_i2c_stop(i2c, 0);
> > }
> > break;
> > @@ -447,7 +469,7 @@ static int i2c_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c,
> > unsigned long iicstat)
> > i2c->msg->buf[i2c->msg_ptr++] = byte;
> >
> > prepare_read:
> > - if (is_msglast(i2c)) {
> > + if (is_msglast(i2c) && is_master(i2c)) {
> > /* last byte of buffer */
> >
> > if (is_lastmsg(i2c))
> > @@ -612,11 +634,13 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
> > if (i2c->suspended)
> > return -EIO;
> >
> > - ret = s3c24xx_i2c_set_master(i2c);
> > - if (ret != 0) {
> > - dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
> > - ret = -EAGAIN;
> > - goto out;
> > + if (is_master(i2c)) {
> > + ret = s3c24xx_i2c_set_master(i2c);
> > + if (ret != 0) {
> > + dev_err(i2c->dev, "cannot get bus (error %d)\n",
> > ret);
> > + ret = -EAGAIN;
> > + goto out;
> > + }
> > }
> >
> > i2c->msg = msgs;
> > @@ -628,23 +652,29 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
> > s3c24xx_i2c_enable_irq(i2c);
> > s3c24xx_i2c_message_start(i2c, msgs);
> >
> > - timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);
> > + if (is_master(i2c))
> > + timeout = wait_event_timeout(i2c->wait,\
> > + i2c->msg_num == 0, HZ * 5);
> > + else
> > + wait_event_interruptible(i2c->wait, i2c->msg_num == 0);
> >
> > ret = i2c->msg_idx;
> >
> > /* having these next two as dev_err() makes life very
> > * noisy when doing an i2cdetect */
> >
> > - if (timeout == 0)
> > - dev_dbg(i2c->dev, "timeout\n");
> > - else if (ret != num)
> > - dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
> > + if (is_master(i2c)) {
> > + if (timeout == 0)
> > + dev_dbg(i2c->dev, "timeout\n");
> > + else if (ret != num)
> > + dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);
> >
> > - /* For QUIRK_HDMIPHY, bus is already disabled */
> > - if (i2c->quirks & QUIRK_HDMIPHY)
> > - goto out;
> > + /* For QUIRK_HDMIPHY, bus is already disabled */
> > + if (i2c->quirks & QUIRK_HDMIPHY)
> > + goto out;
> >
> > - s3c24xx_i2c_wait_idle(i2c);
> > + s3c24xx_i2c_wait_idle(i2c);
> > + }
> >
> > out:
> > return ret;
> > @@ -963,6 +993,7 @@ s3c24xx_i2c_parse_dt(struct device_node *np, struct
> > s3c24xx_i2c *i2c)
> > of_property_read_u32(np, "samsung,i2c-slave-addr",
> > &pdata->slave_addr);
> > of_property_read_u32(np, "samsung,i2c-max-bus-freq",
> > (u32 *)&pdata->frequency);
> > + of_property_read_u32(np, "samsung,i2c-mode", &i2c->i2c_mode);
> > }
> > #else
> > static void
> > @@ -1004,6 +1035,10 @@ static int s3c24xx_i2c_probe(struct platform_device
> > *pdev)
> > goto err_noclk;
> > }
> >
> > + /* By default, i2c works in master mode */
> > + /* This currently will be updated using DT */
> > + i2c->i2c_mode = 0;
> > +
> > i2c->quirks = s3c24xx_get_device_quirks(pdev);
> > if (pdata)
> > memcpy(i2c->pdata, pdata, sizeof(*pdata));
> > @@ -1017,6 +1052,7 @@ static int s3c24xx_i2c_probe(struct platform_device
> > *pdev)
> > i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
> > i2c->tx_setup = 50;
> >
> > +
> > init_waitqueue_head(&i2c->wait);
> >
> > /* find the clock and enable it */
> > --
> > 1.7.9.5
--
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