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Subject[PATCH V4 7/8] backlight: qcom-wled: add support for short circuit handling
Date
Handle the short circuit interrupt and check if the short circuit
interrupt is valid. Re-enable the module to check if it goes
away. Disable the module altogether if the short circuit event
persists.

Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---
Changes from V3:
- Added Reviewed by tag.
- Addressed minor comments from Vinod

drivers/video/backlight/qcom-wled.c | 132 ++++++++++++++++++++++++++++++++++--
1 file changed, 128 insertions(+), 4 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index 362d254..a14f1a6 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -10,6 +10,9 @@
* GNU General Public License for more details.
*/

+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/ktime.h>
#include <linux/kernel.h>
#include <linux/backlight.h>
#include <linux/module.h>
@@ -64,6 +67,16 @@
#define WLED3_SINK_REG_STR_CABC(n) (0x66 + (n * 0x10))
#define WLED3_SINK_REG_STR_CABC_MASK BIT(7)

+/* WLED4 specific control registers */
+#define WLED4_CTRL_REG_SHORT_PROTECT 0x5e
+#define WLED4_CTRL_REG_SHORT_EN_MASK BIT(7)
+
+#define WLED4_CTRL_REG_SEC_ACCESS 0xd0
+#define WLED4_CTRL_REG_SEC_UNLOCK 0xa5
+
+#define WLED4_CTRL_REG_TEST1 0xe2
+#define WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2 0x09
+
/* WLED4 specific sink registers */
#define WLED4_SINK_REG_CURR_SINK 0x46
#define WLED4_SINK_REG_CURR_SINK_MASK GENMASK(7, 4)
@@ -113,17 +126,23 @@ struct wled_config {
bool cs_out_en;
bool ext_gen;
bool cabc;
+ bool external_pfet;
};

struct wled {
const char *name;
struct device *dev;
struct regmap *regmap;
+ struct mutex lock; /* Lock to avoid race from thread irq handler */
+ ktime_t last_short_event;
u16 ctrl_addr;
u16 sink_addr;
u16 max_string_count;
u32 brightness;
u32 max_brightness;
+ u32 short_count;
+ bool disabled_by_short;
+ bool has_short_detect;

struct wled_config cfg;
int (*wled_set_brightness)(struct wled *wled, u16 brightness);
@@ -174,6 +193,9 @@ static int wled_module_enable(struct wled *wled, int val)
{
int rc;

+ if (wled->disabled_by_short)
+ return -EFAULT;
+
rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
WLED_CTRL_REG_MOD_EN,
WLED_CTRL_REG_MOD_EN_MASK,
@@ -210,18 +232,19 @@ static int wled_update_status(struct backlight_device *bl)
bl->props.state & BL_CORE_FBBLANK)
brightness = 0;

+ mutex_lock(&wled->lock);
if (brightness) {
rc = wled->wled_set_brightness(wled, brightness);
if (rc < 0) {
dev_err(wled->dev, "wled failed to set brightness rc:%d\n",
rc);
- return rc;
+ goto unlock_mutex;
}

rc = wled_sync_toggle(wled);
if (rc < 0) {
dev_err(wled->dev, "wled sync failed rc:%d\n", rc);
- return rc;
+ goto unlock_mutex;
}
}

@@ -229,15 +252,61 @@ static int wled_update_status(struct backlight_device *bl)
rc = wled_module_enable(wled, !!brightness);
if (rc < 0) {
dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
- return rc;
+ goto unlock_mutex;
}
}

wled->brightness = brightness;

+unlock_mutex:
+ mutex_unlock(&wled->lock);
+
return rc;
}

+#define WLED_SHORT_DLY_MS 20
+#define WLED_SHORT_CNT_MAX 5
+#define WLED_SHORT_RESET_CNT_DLY_US USEC_PER_SEC
+
+static irqreturn_t wled_short_irq_handler(int irq, void *_wled)
+{
+ struct wled *wled = _wled;
+ int rc;
+ s64 elapsed_time;
+
+ wled->short_count++;
+ mutex_lock(&wled->lock);
+ rc = wled_module_enable(wled, false);
+ if (rc < 0) {
+ dev_err(wled->dev, "wled disable failed rc:%d\n", rc);
+ goto unlock_mutex;
+ }
+
+ elapsed_time = ktime_us_delta(ktime_get(),
+ wled->last_short_event);
+ if (elapsed_time > WLED_SHORT_RESET_CNT_DLY_US)
+ wled->short_count = 0;
+
+ if (wled->short_count > WLED_SHORT_CNT_MAX) {
+ dev_err(wled->dev, "Short trigged %d times, disabling WLED forever!\n",
+ wled->short_count);
+ wled->disabled_by_short = true;
+ goto unlock_mutex;
+ }
+
+ wled->last_short_event = ktime_get();
+
+ msleep(WLED_SHORT_DLY_MS);
+ rc = wled_module_enable(wled, true);
+ if (rc < 0)
+ dev_err(wled->dev, "wled enable failed rc:%d\n", rc);
+
+unlock_mutex:
+ mutex_unlock(&wled->lock);
+
+ return IRQ_HANDLED;
+}
+
static int wled3_setup(struct wled *wled)
{
u16 addr;
@@ -325,7 +394,7 @@ static int wled4_setup(struct wled *wled)
int rc, temp, i, j;
u16 addr;
u8 sink_en = 0;
- u32 sink_cfg = 0;
+ u32 sink_cfg;

rc = regmap_update_bits(wled->regmap,
wled->ctrl_addr + WLED_CTRL_REG_OVP,
@@ -347,6 +416,21 @@ static int wled4_setup(struct wled *wled)
if (rc < 0)
return rc;

+ if (wled->cfg.external_pfet) {
+ /* Unlock the secure register access */
+ rc = regmap_write(wled->regmap, wled->ctrl_addr +
+ WLED4_CTRL_REG_SEC_ACCESS,
+ WLED4_CTRL_REG_SEC_UNLOCK);
+ if (rc < 0)
+ return rc;
+
+ rc = regmap_write(wled->regmap,
+ wled->ctrl_addr + WLED4_CTRL_REG_TEST1,
+ WLED4_CTRL_REG_TEST1_EXT_FET_DTEST2);
+ if (rc < 0)
+ return rc;
+ }
+
rc = regmap_read(wled->regmap, wled->sink_addr +
WLED4_SINK_REG_CURR_SINK, &sink_cfg);
if (rc < 0)
@@ -432,6 +516,7 @@ static int wled4_setup(struct wled *wled)
.num_strings = 4,
.switch_freq = 11,
.cabc = false,
+ .external_pfet = false,
};

static const u32 wled3_boost_i_limit_values[] = {
@@ -600,6 +685,7 @@ static int wled_configure(struct wled *wled, int version)
{ "qcom,cs-out", &cfg->cs_out_en, },
{ "qcom,ext-gen", &cfg->ext_gen, },
{ "qcom,cabc", &cfg->cabc, },
+ { "qcom,external-pfet", &cfg->external_pfet, },
};

prop_addr = of_get_address(dev->of_node, 0, NULL, NULL);
@@ -688,6 +774,38 @@ static int wled_configure(struct wled *wled, int version)
return 0;
}

+static int wled_configure_short_irq(struct wled *wled,
+ struct platform_device *pdev)
+{
+ int rc, short_irq;
+
+ if (!wled->has_short_detect)
+ return 0;
+
+ rc = regmap_update_bits(wled->regmap, wled->ctrl_addr +
+ WLED4_CTRL_REG_SHORT_PROTECT,
+ WLED4_CTRL_REG_SHORT_EN_MASK,
+ WLED4_CTRL_REG_SHORT_EN_MASK);
+ if (rc < 0)
+ return rc;
+
+ short_irq = platform_get_irq_byname(pdev, "short");
+ if (short_irq < 0) {
+ dev_dbg(&pdev->dev, "short irq is not used\n");
+ return 0;
+ }
+
+ rc = devm_request_threaded_irq(wled->dev, short_irq,
+ NULL, wled_short_irq_handler,
+ IRQF_ONESHOT,
+ "wled_short_irq", wled);
+ if (rc < 0)
+ dev_err(wled->dev, "Unable to request short_irq (err:%d)\n",
+ rc);
+
+ return rc;
+}
+
static const struct backlight_ops wled_ops = {
.update_status = wled_update_status,
};
@@ -721,6 +839,7 @@ static int wled_probe(struct platform_device *pdev)
return -ENODEV;
}

+ mutex_init(&wled->lock);
rc = wled_configure(wled, version);
if (rc)
return rc;
@@ -735,6 +854,7 @@ static int wled_probe(struct platform_device *pdev)
break;

case WLED4:
+ wled->has_short_detect = true;
rc = wled4_setup(wled);
if (rc) {
dev_err(&pdev->dev, "wled4_setup failed\n");
@@ -747,6 +867,10 @@ static int wled_probe(struct platform_device *pdev)
break;
}

+ rc = wled_configure_short_irq(wled, pdev);
+ if (rc < 0)
+ return rc;
+
val = WLED_DEFAULT_BRIGHTNESS;
of_property_read_u32(pdev->dev.of_node, "default-brightness", &val);

--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
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