All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ben Warren <biggerbadderben@gmail.com>
To: u-boot@lists.denx.de
Subject: [U-Boot-Users] MPC8xx I2C
Date: Wed, 30 Jan 2008 11:33:56 -0500	[thread overview]
Message-ID: <47A0A6F4.4010402@gmail.com> (raw)

Hi,

I'm trying to rationalize some very common I2C code and came across the 
following:

Every controller except cpu/mpc8xx implements functions like this:

---

uchar i2c_reg_read(uchar i2c_addr, uchar reg)
{
	uchar buf;

	i2c_read(i2c_addr, reg, 1, &buf, 1);
	return buf;
}

void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
{
	i2c_write(i2c_addr, reg, 1, &val, 1);
}


---

cpu/mpc8xx, however, adds i2c_init() calls:

---

uchar i2c_reg_read(uchar i2c_addr, uchar reg)
{
	uchar buf;

	i2c_init(CFG_I2C_SPEED, CFG_I2C_SLAVE);
	i2c_read(i2c_addr, reg, 1, &buf, 1);
	return (buf);
}

void i2c_reg_write(uchar i2c_addr, uchar reg, uchar val)
{
	i2c_init(CFG_I2C_SPEED, CFG_I2C_SLAVE);
	i2c_write(i2c_addr, reg, 1, &val, 1);
}

---

Can somebody lend historical perspective as to why these i2c_init() 
calls are needed?

thanks,
Ben

                 reply	other threads:[~2008-01-30 16:33 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=47A0A6F4.4010402@gmail.com \
    --to=biggerbadderben@gmail.com \
    --cc=u-boot@lists.denx.de \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.