linux-i2c.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Griffin <peter.griffin@linaro.org>
To: linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, srinivas.kandagatla@gmail.com,
	maxime.coquelin@st.com, patrice.chotard@st.com,
	wsa@the-dreams.de
Cc: peter.griffin@linaro.org, lee.jones@linaro.org,
	linux-i2c@vger.kernel.org,
	Frederic Pillon <frederic.pillon@st.com>
Subject: [PATCH] i2c: st: Implement i2c_bus_recovery_info callbacks
Date: Tue, 12 Apr 2016 14:29:19 +0100	[thread overview]
Message-ID: <1460467759-11737-1-git-send-email-peter.griffin@linaro.org> (raw)

>From I2C specification:

http://www.nxp.com/documents/user_manual/UM10204.pdf

Rev. 03 section 3.1.16 titled "Bus clear". When the i2c device held the
SDA line low, the master should send 9 clocks pulses to try to recover.

Signed-off-by: Frederic Pillon <frederic.pillon@st.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
---
 drivers/i2c/busses/i2c-st.c | 56 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 55 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-st.c b/drivers/i2c/busses/i2c-st.c
index 6ee7715..37b0b34 100644
--- a/drivers/i2c/busses/i2c-st.c
+++ b/drivers/i2c/busses/i2c-st.c
@@ -337,10 +337,51 @@ static void st_i2c_hw_config(struct st_i2c_dev *i2c_dev)
 	writel_relaxed(val, i2c_dev->base + SSC_NOISE_SUPP_WIDTH_DATAOUT);
 }
 
+/*
+ * i2c bus recovery routines
+ * get_scl and set_scl must be defined to avoid the recover_bus field of
+ * i2c_bus_recovery_info to be overriden with NULL during the
+ * i2c_add_adapter call
+ */
+
+static int st_i2c_get_scl(struct i2c_adapter *adap)
+{
+	return 0;
+}
+
+static void st_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+}
+
+static int st_i2c_recover_bus(struct i2c_adapter *i2c_adap)
+{
+	struct st_i2c_dev *i2c_dev = i2c_get_adapdata(i2c_adap);
+	u32 ctl;
+
+	dev_err(i2c_dev->dev, "Trying to recover bus\n");
+
+	/* Disable interrupts */
+	writel_relaxed(0, i2c_dev->base + SSC_IEN);
+
+	st_i2c_hw_config(i2c_dev);
+
+	ctl = SSC_CTL_EN | SSC_CTL_MS |	SSC_CTL_EN_RX_FIFO | SSC_CTL_EN_TX_FIFO;
+	st_i2c_set_bits(i2c_dev->base + SSC_CTL, ctl);
+
+	st_i2c_clr_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
+	usleep_range(8000, 10000);
+
+	writel_relaxed(0, i2c_dev->base + SSC_TBUF);
+	usleep_range(2000, 4000);
+	st_i2c_set_bits(i2c_dev->base + SSC_I2C, SSC_I2C_I2CM);
+
+	return 0;
+}
+
 static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
 {
 	u32 sta;
-	int i;
+	int i, ret;
 
 	for (i = 0; i < 10; i++) {
 		sta = readl_relaxed(i2c_dev->base + SSC_STA);
@@ -352,6 +393,12 @@ static int st_i2c_wait_free_bus(struct st_i2c_dev *i2c_dev)
 
 	dev_err(i2c_dev->dev, "bus not free (status = 0x%08x)\n", sta);
 
+	ret = i2c_recover_bus(&i2c_dev->adap);
+	if (ret) {
+		dev_err(i2c_dev->dev, "Failed to recover the bus (%d)\n", ret);
+		return ret;
+	}
+
 	return -EBUSY;
 }
 
@@ -744,6 +791,12 @@ static struct i2c_algorithm st_i2c_algo = {
 	.functionality = st_i2c_func,
 };
 
+static struct i2c_bus_recovery_info st_i2c_recovery_info = {
+	.recover_bus = st_i2c_recover_bus,
+	.get_scl =  st_i2c_get_scl,
+	.set_scl =  st_i2c_set_scl,
+};
+
 static int st_i2c_of_get_deglitch(struct device_node *np,
 		struct st_i2c_dev *i2c_dev)
 {
@@ -826,6 +879,7 @@ static int st_i2c_probe(struct platform_device *pdev)
 	adap->timeout = 2 * HZ;
 	adap->retries = 0;
 	adap->algo = &st_i2c_algo;
+	adap->bus_recovery_info = &st_i2c_recovery_info;
 	adap->dev.parent = &pdev->dev;
 	adap->dev.of_node = pdev->dev.of_node;
 
-- 
1.9.1

             reply	other threads:[~2016-04-12 13:29 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-12 13:29 Peter Griffin [this message]
2016-04-24 21:10 ` [PATCH] i2c: st: Implement i2c_bus_recovery_info callbacks Wolfram Sang
2016-04-28 13:30   ` Maxime Coquelin
2016-04-28 14:57     ` Wolfram Sang
2016-04-29 11:26       ` Maxime Coquelin
2016-04-29 14:03         ` Peter Griffin
2016-05-11 15:01           ` Wolfram Sang
2016-05-11 15:26             ` Peter Griffin
2016-05-11 16:22   ` Peter Griffin

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=1460467759-11737-1-git-send-email-peter.griffin@linaro.org \
    --to=peter.griffin@linaro.org \
    --cc=frederic.pillon@st.com \
    --cc=lee.jones@linaro.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-i2c@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=maxime.coquelin@st.com \
    --cc=patrice.chotard@st.com \
    --cc=srinivas.kandagatla@gmail.com \
    --cc=wsa@the-dreams.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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).