--- /dev/null
+From b6494e2070983020d56f82d9d0be74d11b001823 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org>
+Date: Tue, 1 Nov 2016 15:15:41 +0100
+Subject: [PATCH] i2c: bcm2835: Add debug support
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This adds a debug module parameter to aid in debugging transfer issues
+by printing info to the kernel log. When enabled, status values are
+collected in the interrupt routine and msg info in
+bcm2835_i2c_start_transfer(). This is done in a way that tries to avoid
+affecting timing. Having printk in the isr can mask issues.
+
+debug values (additive):
+1: Print info on error
+2: Print info on all transfers
+3: Print messages before transfer is started
+
+The value can be changed at runtime:
+/sys/module/i2c_bcm2835/parameters/debug
+
+Example output, debug=3:
+[ 747.114448] bcm2835_i2c_xfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
+[ 747.114463] bcm2835_i2c_xfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
+[ 747.117809] start_transfer: msg(1/2) write addr=0x54, len=2 flags= [i2c1]
+[ 747.117825] isr: remain=2, status=0x30000055 : TA TXW TXD TXE [i2c1]
+[ 747.117839] start_transfer: msg(2/2) read addr=0x54, len=32 flags= [i2c1]
+[ 747.117849] isr: remain=32, status=0xd0000039 : TA RXR TXD RXD [i2c1]
+[ 747.117861] isr: remain=20, status=0xd0000039 : TA RXR TXD RXD [i2c1]
+[ 747.117870] isr: remain=8, status=0x32 : DONE TXD RXD [i2c1]
+
+Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
+---
+ drivers/i2c/busses/i2c-bcm2835.c | 99 +++++++++++++++++++++++++++++++-
+ 1 file changed, 98 insertions(+), 1 deletion(-)
+
+--- a/drivers/i2c/busses/i2c-bcm2835.c
++++ b/drivers/i2c/busses/i2c-bcm2835.c
+@@ -56,6 +56,18 @@
+ #define BCM2835_I2C_CDIV_MIN 0x0002
+ #define BCM2835_I2C_CDIV_MAX 0xFFFE
+
++static unsigned int debug;
++module_param(debug, uint, 0644);
++MODULE_PARM_DESC(debug, "1=err, 2=isr, 3=xfer");
++
++#define BCM2835_DEBUG_MAX 512
++struct bcm2835_debug {
++ struct i2c_msg *msg;
++ int msg_idx;
++ size_t remain;
++ u32 status;
++};
++
+ struct bcm2835_i2c_dev {
+ struct device *dev;
+ void __iomem *regs;
+@@ -69,8 +81,78 @@ struct bcm2835_i2c_dev {
+ u32 msg_err;
+ u8 *msg_buf;
+ size_t msg_buf_remaining;
++ struct bcm2835_debug debug[BCM2835_DEBUG_MAX];
++ unsigned int debug_num;
++ unsigned int debug_num_msgs;
+ };
+
++static inline void bcm2835_debug_add(struct bcm2835_i2c_dev *i2c_dev, u32 s)
++{
++ if (!i2c_dev->debug_num_msgs || i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
++ return;
++
++ i2c_dev->debug[i2c_dev->debug_num].msg = i2c_dev->curr_msg;
++ i2c_dev->debug[i2c_dev->debug_num].msg_idx =
++ i2c_dev->debug_num_msgs - i2c_dev->num_msgs;
++ i2c_dev->debug[i2c_dev->debug_num].remain = i2c_dev->msg_buf_remaining;
++ i2c_dev->debug[i2c_dev->debug_num].status = s;
++ i2c_dev->debug_num++;
++}
++
++static void bcm2835_debug_print_status(struct bcm2835_i2c_dev *i2c_dev,
++ struct bcm2835_debug *d)
++{
++ u32 s = d->status;
++
++ pr_info("isr: remain=%zu, status=0x%x : %s%s%s%s%s%s%s%s%s%s [i2c%d]\n",
++ d->remain, s,
++ s & BCM2835_I2C_S_TA ? "TA " : "",
++ s & BCM2835_I2C_S_DONE ? "DONE " : "",
++ s & BCM2835_I2C_S_TXW ? "TXW " : "",
++ s & BCM2835_I2C_S_RXR ? "RXR " : "",
++ s & BCM2835_I2C_S_TXD ? "TXD " : "",
++ s & BCM2835_I2C_S_RXD ? "RXD " : "",
++ s & BCM2835_I2C_S_TXE ? "TXE " : "",
++ s & BCM2835_I2C_S_RXF ? "RXF " : "",
++ s & BCM2835_I2C_S_ERR ? "ERR " : "",
++ s & BCM2835_I2C_S_CLKT ? "CLKT " : "",
++ i2c_dev->adapter.nr);
++}
++
++static void bcm2835_debug_print_msg(struct bcm2835_i2c_dev *i2c_dev,
++ struct i2c_msg *msg, int i, int total,
++ const char *fname)
++{
++ pr_info("%s: msg(%d/%d) %s addr=0x%02x, len=%u flags=%s%s%s%s%s%s%s [i2c%d]\n",
++ fname, i, total,
++ msg->flags & I2C_M_RD ? "read" : "write", msg->addr, msg->len,
++ msg->flags & I2C_M_TEN ? "TEN" : "",
++ msg->flags & I2C_M_RECV_LEN ? "RECV_LEN" : "",
++ msg->flags & I2C_M_NO_RD_ACK ? "NO_RD_ACK" : "",
++ msg->flags & I2C_M_IGNORE_NAK ? "IGNORE_NAK" : "",
++ msg->flags & I2C_M_REV_DIR_ADDR ? "REV_DIR_ADDR" : "",
++ msg->flags & I2C_M_NOSTART ? "NOSTART" : "",
++ msg->flags & I2C_M_STOP ? "STOP" : "",
++ i2c_dev->adapter.nr);
++}
++
++static void bcm2835_debug_print(struct bcm2835_i2c_dev *i2c_dev)
++{
++ struct bcm2835_debug *d;
++ unsigned int i;
++
++ for (i = 0; i < i2c_dev->debug_num; i++) {
++ d = &i2c_dev->debug[i];
++ if (d->status == ~0)
++ bcm2835_debug_print_msg(i2c_dev, d->msg, d->msg_idx,
++ i2c_dev->debug_num_msgs, "start_transfer");
++ else
++ bcm2835_debug_print_status(i2c_dev, d);
++ }
++ if (i2c_dev->debug_num >= BCM2835_DEBUG_MAX)
++ pr_info("BCM2835_DEBUG_MAX reached\n");
++}
++
+ static inline void bcm2835_i2c_writel(struct bcm2835_i2c_dev *i2c_dev,
+ u32 reg, u32 val)
+ {
+@@ -189,6 +271,7 @@ static void bcm2835_i2c_start_transfer(s
+ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_A, msg->addr);
+ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DLEN, msg->len);
+ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C, c);
++ bcm2835_debug_add(i2c_dev, ~0);
+ }
+
+ static void bcm2835_i2c_finish_transfer(struct bcm2835_i2c_dev *i2c_dev)
+@@ -215,6 +298,7 @@ static irqreturn_t bcm2835_i2c_isr(int t
+ u32 val, err;
+
+ val = bcm2835_i2c_readl(i2c_dev, BCM2835_I2C_S);
++ bcm2835_debug_add(i2c_dev, val);
+
+ err = val & (BCM2835_I2C_S_CLKT | BCM2835_I2C_S_ERR);
+ if (err) {
+@@ -281,6 +365,13 @@ static int bcm2835_i2c_xfer(struct i2c_a
+ unsigned long time_left;
+ int i, ret;
+
++ if (debug)
++ i2c_dev->debug_num_msgs = num;
++
++ if (debug > 2)
++ for (i = 0; i < num; i++)
++ bcm2835_debug_print_msg(i2c_dev, &msgs[i], i + 1, num, __func__);
++
+ for (i = 0; i < (num - 1); i++)
+ if (msgs[i].flags & I2C_M_RD) {
+ dev_warn_once(i2c_dev->dev,
+@@ -303,6 +394,10 @@ static int bcm2835_i2c_xfer(struct i2c_a
+
+ bcm2835_i2c_finish_transfer(i2c_dev);
+
++ if (debug > 1 || (debug && (!time_left || i2c_dev->msg_err)))
++ bcm2835_debug_print(i2c_dev);
++ i2c_dev->debug_num_msgs = 0;
++ i2c_dev->debug_num = 0;
+ if (!time_left) {
+ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_C,
+ BCM2835_I2C_C_CLEAR);
+@@ -313,7 +408,9 @@ static int bcm2835_i2c_xfer(struct i2c_a
+ if (!i2c_dev->msg_err)
+ return num;
+
+- dev_dbg(i2c_dev->dev, "i2c transfer failed: %x\n", i2c_dev->msg_err);
++ if (debug)
++ dev_err(i2c_dev->dev, "i2c transfer failed: %x\n",
++ i2c_dev->msg_err);
+
+ if (i2c_dev->msg_err & BCM2835_I2C_S_ERR)
+ return -EREMOTEIO;
projects / openwrt / staging / chunkeey.git / blobdiff