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Message-ID: <20180625161303.7991-4-federico.vaga@cern.ch>
Date: Mon, 25 Jun 2018 18:13:03 +0200
From: Federico Vaga <federico.vaga@...n.ch>
To: <linux-i2c@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
"Peter Korsgaard" <jacmet@...site.dk>
CC: <federico.vaga@...n.ch>
Subject: [PATCH 3/3] i2c:ocores: add polling interface
This driver assumes that an interrupt line is always available for
the I2C master. This is not always the case and this patch adds support
for a polling version based on workqueue.
Signed-off-by: Federico Vaga <federico.vaga@...n.ch>
---
drivers/i2c/busses/i2c-ocores.c | 94 ++++++++++++++++++++++++++++++++++-------
1 file changed, 79 insertions(+), 15 deletions(-)
diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index 274d6eb22a2c..0dad1a512ef5 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -13,6 +13,7 @@
*/
#include <linux/clk.h>
+#include <linux/delay.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>
@@ -26,14 +27,19 @@
#include <linux/io.h>
#include <linux/log2.h>
#include <linux/spinlock.h>
+#include <linux/workqueue.h>
+
+#define OCORES_FLAG_POLL BIT(0)
struct ocores_i2c {
void __iomem *base;
u32 reg_shift;
u32 reg_io_width;
+ unsigned long flags;
wait_queue_head_t wait;
struct i2c_adapter adap;
struct i2c_msg *msg;
+ struct work_struct xfer_work;
int pos;
int nmsgs;
int state; /* see STATE_ */
@@ -166,8 +172,9 @@ static void ocores_process(struct ocores_i2c *i2c, u8 stat)
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_STOP);
return;
}
- } else
+ } else {
msg->buf[i2c->pos++] = oc_getreg(i2c, OCI2C_DATA);
+ }
/* end of msg? */
if (i2c->pos == msg->len) {
@@ -232,6 +239,50 @@ static irqreturn_t ocores_isr(int irq, void *dev_id)
return IRQ_HANDLED;
}
+
+/**
+ * It waits until is possible to process some data
+ * @i2c: ocores I2C device instance
+ *
+ * This is used when the device is in polling mode (interrupts disabled).
+ * It sleeps for the time necessary to send 8bits (one transfer over
+ * the I2C bus), then it permanently ping the ip-core until is possible
+ * to process data. The idea is that we sleep for most of the time at the
+ * beginning because we are sure that the ip-core is not ready yet.
+ */
+static void ocores_poll_wait(struct ocores_i2c *i2c)
+{
+ int sleep_min = (8/i2c->bus_clock_khz) * 1000; /* us for 8bits */
+ u8 loop_on;
+
+ usleep_range(sleep_min, sleep_min + 10);
+ if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)
+ loop_on = OCI2C_STAT_BUSY;
+ else
+ loop_on = OCI2C_STAT_TIP;
+ while (oc_getreg(i2c, OCI2C_STATUS) & loop_on)
+ ;
+}
+
+
+/**
+ * It implements the polling logic
+ * @work: work instance descriptor
+ *
+ * Here we try to re-use as much as possible from the IRQ logic
+ */
+static void ocores_work(struct work_struct *work)
+{
+ struct ocores_i2c *i2c = container_of(work,
+ struct ocores_i2c, xfer_work);
+ irqreturn_t ret;
+
+ do {
+ ocores_poll_wait(i2c);
+ ret = ocores_isr(-1, i2c);
+ } while (ret != IRQ_NONE);
+}
+
static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
struct ocores_i2c *i2c = i2c_get_adapdata(adap);
@@ -245,6 +296,9 @@ static int ocores_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
oc_setreg(i2c, OCI2C_DATA, i2c_8bit_addr_from_msg(i2c->msg));
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_START);
+ if (i2c->flags & OCORES_FLAG_POLL)
+ schedule_work(&i2c->xfer_work);
+
if (wait_event_timeout(i2c->wait, (i2c->state == STATE_ERROR) ||
(i2c->state == STATE_DONE), HZ)) {
return (i2c->state == STATE_DONE) ? num : -EIO;
@@ -264,7 +318,8 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c)
u8 ctrl = oc_getreg(i2c, OCI2C_CONTROL);
/* make sure the device is disabled */
- oc_setreg(i2c, OCI2C_CONTROL, ctrl & ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
+ ctrl &= ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN);
+ oc_setreg(i2c, OCI2C_CONTROL, ctrl);
prescale = (i2c->ip_clock_khz / (5 * i2c->bus_clock_khz)) - 1;
prescale = clamp(prescale, 0, 0xffff);
@@ -277,12 +332,16 @@ static int ocores_init(struct device *dev, struct ocores_i2c *i2c)
return -EINVAL;
}
+
oc_setreg(i2c, OCI2C_PRELOW, prescale & 0xff);
oc_setreg(i2c, OCI2C_PREHIGH, prescale >> 8);
/* Init the device */
oc_setreg(i2c, OCI2C_CMD, OCI2C_CMD_IACK);
- oc_setreg(i2c, OCI2C_CONTROL, ctrl | OCI2C_CTRL_IEN | OCI2C_CTRL_EN);
+ ctrl |= OCI2C_CTRL_EN;
+ if (i2c->flags != OCORES_FLAG_POLL)
+ ctrl |= OCI2C_CTRL_IEN;
+ oc_setreg(i2c, OCI2C_CONTROL, ctrl);
return 0;
}
@@ -439,10 +498,6 @@ static int ocores_i2c_probe(struct platform_device *pdev)
int ret;
int i;
- irq = platform_get_irq(pdev, 0);
- if (irq < 0)
- return irq;
-
i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
@@ -497,18 +552,25 @@ static int ocores_i2c_probe(struct platform_device *pdev)
}
}
+ init_waitqueue_head(&i2c->wait);
+
+ irq = platform_get_irq(pdev, 0);
+ if (irq == -ENXIO) {
+ i2c->flags |= OCORES_FLAG_POLL;
+ INIT_WORK(&i2c->xfer_work, ocores_work);
+ } else {
+ ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
+ pdev->name, i2c);
+ if (ret) {
+ dev_err(&pdev->dev, "Cannot claim IRQ\n");
+ goto err_clk;
+ }
+ }
+
ret = ocores_init(&pdev->dev, i2c);
if (ret)
goto err_clk;
- init_waitqueue_head(&i2c->wait);
- ret = devm_request_irq(&pdev->dev, irq, ocores_isr, 0,
- pdev->name, i2c);
- if (ret) {
- dev_err(&pdev->dev, "Cannot claim IRQ\n");
- goto err_clk;
- }
-
/* hook up driver to tree */
platform_set_drvdata(pdev, i2c);
i2c->adap = ocores_adapter;
@@ -538,6 +600,8 @@ static int ocores_i2c_remove(struct platform_device *pdev)
{
struct ocores_i2c *i2c = platform_get_drvdata(pdev);
+ flush_scheduled_work();
+
/* disable i2c logic */
oc_setreg(i2c, OCI2C_CONTROL, oc_getreg(i2c, OCI2C_CONTROL)
& ~(OCI2C_CTRL_EN|OCI2C_CTRL_IEN));
--
2.15.0
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