[U-Boot] [EXT] Re: [PATCH] i2c: pcf2127: fix bug that read wrong time
Chuanhua Han
chuanhua.han at nxp.com
Wed May 22 08:28:48 UTC 2019
> -----Original Message-----
> From: Lukasz Majewski <lukma at denx.de>
> Sent: 2019年5月22日 15:16
> To: Chuanhua Han <chuanhua.han at nxp.com>
> Cc: hs at denx.de; u-boot at lists.denx.de; Biwen Li <biwen.li at nxp.com>;
> sjg at chromium.org
> Subject: [EXT] Re: [PATCH] i2c: pcf2127: fix bug that read wrong time
>
> Hi Chuanhua,
>
> > Because i2c driver does not generate a stop bit when reading registers
> > of pcf2127
>
> The change (in the common i2c code) is rather large when considering the
> description above.
>
> Could you write a more detailed patch description? Is this only the problem
> with i2c in DM?
OK, This is a problem with the i2c transport framework. After writing the register
address that you want to read, the stop signal is missing before reading the register data.
>
> Is the same code (as introduced in this commit) available in Linux kernel?
The kernel does not have such a problem
> How the error is reproduced? What are the symptoms of it?
You can use the i2c command to read the register data of pcf2127.
You will find that you want to read the address 0 of the register,
but the data of the 1 address is read, and the data read later will be offset.
>
> In which way the pcf2127 needs special treatment (non I2C compatible)?
> How does it differ from other RTC devices?
According to the pcf2127 chip manual, when you need to read the internal
register data, you need to write the register address first and then
need stop bit(it is necessary).
>
> >
> > Signed-off-by: Biwen Li <biwen.li at nxp.com>
> > Signed-off-by: Chuanhua Han <chuanhua.han at nxp.com>
> > ---
> > drivers/i2c/i2c-uclass.c | 2 ++
> > drivers/i2c/mxc_i2c.c | 70
> > +++++++++++++++++++++++++++++++++++----- drivers/rtc/pcf2127.c |
> > 18 ++++++----- include/i2c.h | 2 ++
> > 4 files changed, 76 insertions(+), 16 deletions(-)
> >
> > diff --git a/drivers/i2c/i2c-uclass.c b/drivers/i2c/i2c-uclass.c index
> > e47abf1833..18f7364d72 100644
> > --- a/drivers/i2c/i2c-uclass.c
> > +++ b/drivers/i2c/i2c-uclass.c
> > @@ -141,6 +141,8 @@ int dm_i2c_read(struct udevice *dev, uint offset,
> > uint8_t *buffer, int len) if (len) {
> > ptr->addr = chip->chip_addr;
> > ptr->flags = chip->flags & DM_I2C_CHIP_10BIT ?
> > I2C_M_TEN : 0;
> > + ptr->flags |= chip->flags &
> > DM_I2C_CHIP_RD_NEED_STOP_BIT ?
> > + I2C_M_RD_NEED_STOP_BIT : 0;
> > ptr->flags |= I2C_M_RD;
> > ptr->len = len;
> > ptr->buf = buffer;
> > diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c index
> > 73b9807598..241367bac8 100644
> > --- a/drivers/i2c/mxc_i2c.c
> > +++ b/drivers/i2c/mxc_i2c.c
> > @@ -962,6 +962,8 @@ static int mxc_i2c_xfer(struct udevice *bus,
> > struct i2c_msg *msg, int nmsgs) int reg_shift = i2c_bus->driver_data &
> > I2C_QUIRK_FLAG ? VF610_I2C_REGSHIFT : IMX_I2C_REGSHIFT;
> > int read_mode;
> > + bool quirk = i2c_bus->driver_data & I2C_QUIRK_FLAG ? true :
> > false;
> > + unsigned int temp;
> >
> > /* Here address len is set to -1 to not send any address at first.
> > * Otherwise i2c_init_transfer will send the chip address with write
> > @@ -976,6 +978,7 @@ static int mxc_i2c_xfer(struct udevice *bus,
> > struct i2c_msg *msg, int nmsgs) read_mode = -1; /* So it's always
> > different on the first message */ for (; nmsgs > 0; nmsgs--,
> > msg++) { const int msg_is_read = !!(msg->flags & I2C_M_RD);
> > + bool next_is_read = nmsgs > 1 && (msg[1].flags &
> > I2C_M_RD);
> > debug("i2c_xfer: chip=0x%x, len=0x%x, dir=%c\n",
> > msg->addr, msg->len, msg_is_read ? 'R' : 'W');
> > @@ -983,13 +986,16 @@ static int mxc_i2c_xfer(struct udevice *bus,
> > struct i2c_msg *msg, int nmsgs) if (msg_is_read != read_mode) {
> > /* Send repeated start if not 1st message */
> > if (read_mode != -1) {
> > - debug("i2c_xfer: [RSTART]\n");
> > - ret = readb(base + (I2CR <<
> > reg_shift));
> > - ret |= I2CR_RSTA;
> > - writeb(ret, base + (I2CR <<
> > reg_shift));
> > + if (!(msg[1].flags &
> > I2C_M_RD_NEED_STOP_BIT)) {
> > + debug("i2c_xfer:
> > [RSTART]\n");
> > + ret = readb(base + (I2CR <<
> > reg_shift));
> > + ret |= I2CR_RSTA;
> > + writeb(ret, base + (I2CR <<
> > reg_shift));
> > + }
> > }
> > debug("i2c_xfer: [ADDR %02x | %c]\n",
> > msg->addr, msg_is_read ? 'R' : 'W');
> > +
> > ret = tx_byte(i2c_bus, (msg->addr << 1) | msg_is_read); if (ret <
> > 0) {
> > debug("i2c_xfer: [STOP]\n");
> > @@ -999,16 +1005,64 @@ static int mxc_i2c_xfer(struct udevice *bus,
> > struct i2c_msg *msg, int nmsgs) read_mode = msg_is_read;
> > }
> >
> > - if (msg->flags & I2C_M_RD)
> > + if (msg->flags & I2C_M_RD) {
> > ret = i2c_read_data(i2c_bus, msg->addr,
> > msg->buf, msg->len, nmsgs == 1 ||
> > (msg->flags &
> > I2C_M_STOP));
> > - else
> > - ret = i2c_write_data(i2c_bus, msg->addr,
> > msg->buf,
> > - msg->len);
> > + if (ret < 0)
> > + break;
> > + continue;
> > + }
> >
> > + /* Write message */
> > + ret = i2c_write_data(i2c_bus, msg->addr, msg->buf,
> > + msg->len);
> > if (ret < 0)
> > break;
> > +
> > + if (!next_is_read)
> > + continue;
> > +
> > + /* Read message following write message */
> > + if (msg[1].flags & I2C_M_RD_NEED_STOP_BIT) {
> > + /* Generate a stop bit */
> > + i2c_imx_stop(i2c_bus);
> > + /* Reset i2c slave */
> > + i2c_force_reset_slave();
> > +
> > + /* Enable I2C controller */
> > + if (quirk)
> > + ret = readb(base + (I2CR <<
> > reg_shift))
> > + & I2CR_IDIS;
> > + else
> > + ret = !(readb(base + (I2CR <<
> > reg_shift))
> > + & I2CR_IEN);
> > + if (ret) {
> > + writeb(I2CR_IEN, base + (I2CR <<
> > reg_shift));
> > + /* Wait for controller to be stable
> > */
> > + udelay(50);
> > + }
> > +
> > + /* Clear interrupt bit */
> > + writeb(I2SR_IIF_CLEAR, base + (I2SR <<
> > reg_shift));
> > + ret = wait_for_sr_state(i2c_bus,
> > ST_BUS_IDLE);
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* Start I2C transaction */
> > + temp = readb(base + (I2CR << reg_shift));
> > + temp |= I2CR_MSTA;
> > + writeb(temp, base + (I2CR << reg_shift));
> > +
> > + ret = wait_for_sr_state(i2c_bus,
> > ST_BUS_BUSY);
> > + if (ret < 0)
> > + return ret;
> > +
> > + /* Enter transfer mode */
> > + temp |= I2CR_MTX | I2CR_TX_NO_AK;
> > + writeb(temp, base + (I2CR << reg_shift));
> > + udelay(50);
> > + }
> > }
> >
> > if (ret)
> > diff --git a/drivers/rtc/pcf2127.c b/drivers/rtc/pcf2127.c index
> > dcf0340b4d..010c45ecbf 100644
> > --- a/drivers/rtc/pcf2127.c
> > +++ b/drivers/rtc/pcf2127.c
> > @@ -24,12 +24,9 @@
> >
> > static int pcf2127_rtc_set(struct udevice *dev, const struct rtc_time
> > *tm) {
> > - uchar buf[8];
> > + uchar buf[7] = {0};
> > int i = 0, ret;
> >
> > - /* start register address */
> > - buf[i++] = PCF2127_REG_SC;
> > -
> > /* hours, minutes and seconds */
> > buf[i++] = bin2bcd(tm->tm_sec);
> > buf[i++] = bin2bcd(tm->tm_min);
> > @@ -44,7 +41,7 @@ static int pcf2127_rtc_set(struct udevice *dev,
> > const struct rtc_time *tm) buf[i++] = bin2bcd(tm->tm_year % 100);
> >
> > /* write register's data */
> > - ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
> > + ret = dm_i2c_write(dev, PCF2127_REG_SC, buf, i);
> >
> > return ret;
> > }
> > @@ -54,9 +51,6 @@ static int pcf2127_rtc_get(struct udevice *dev,
> > struct rtc_time *tm) int ret = 0;
> > uchar buf[10] = { PCF2127_REG_CTRL1 };
> >
> > - ret = dm_i2c_write(dev, PCF2127_REG_CTRL1, buf, 1);
> > - if (ret < 0)
> > - return ret;
> > ret = dm_i2c_read(dev, PCF2127_REG_CTRL1, buf, sizeof(buf));
> > if (ret < 0)
> > return ret;
> > @@ -90,6 +84,13 @@ static int pcf2127_rtc_reset(struct udevice *dev)
> > return 0;
> > }
> >
> > +static int pcf2127_probe(struct udevice *dev) {
> > + i2c_set_chip_flags(dev, DM_I2C_CHIP_RD_NEED_STOP_BIT);
> > +
> > + return 0;
> > +}
> > +
> > static const struct rtc_ops pcf2127_rtc_ops = {
> > .get = pcf2127_rtc_get,
> > .set = pcf2127_rtc_set,
> > @@ -104,6 +105,7 @@ static const struct udevice_id pcf2127_rtc_ids[] =
> > { U_BOOT_DRIVER(rtc_pcf2127) = {
> > .name = "rtc-pcf2127",
> > .id = UCLASS_RTC,
> > + .probe = pcf2127_probe,
> > .of_match = pcf2127_rtc_ids,
> > .ops = &pcf2127_rtc_ops,
> > };
> > diff --git a/include/i2c.h b/include/i2c.h index
> > a5c760c711..beaa028349 100644
> > --- a/include/i2c.h
> > +++ b/include/i2c.h
> > @@ -28,6 +28,7 @@ enum dm_i2c_chip_flags {
> > DM_I2C_CHIP_10BIT = 1 << 0, /* Use 10-bit addressing
> > */ DM_I2C_CHIP_RD_ADDRESS = 1 << 1, /* Send address for each
> > read byte */ DM_I2C_CHIP_WR_ADDRESS = 1 << 2, /* Send address
> > for each write byte */
> > + DM_I2C_CHIP_RD_NEED_STOP_BIT = 1 << 3, /* Need generate
> > stop bit */ };
> >
> > struct udevice;
> > @@ -87,6 +88,7 @@ enum dm_i2c_msg_flags {
> > I2C_M_IGNORE_NAK = 0x1000, /* continue after NAK */
> > I2C_M_NO_RD_ACK = 0x0800, /* skip the Ack bit
> > on reads */ I2C_M_RECV_LEN = 0x0400, /* length is
> > first received byte */
> > + I2C_M_RD_NEED_STOP_BIT = 0x0002, /* need generate stop bit
> > */ };
> >
> > /**
>
>
>
>
> Best regards,
>
> Lukasz Majewski
>
> --
>
> DENX Software Engineering GmbH, Managing Director: Wolfgang Denk
> HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-59 Fax: (+49)-8142-66989-80 Email:
> lukma at denx.de
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