charger: tps65090: Allow charger module to be used when no irq

On the ARM Chromebook tps65090 has two masters: the AP (the main
processor running linux) and the EC (the embedded controller).  The AP
is allowed to mess with FETs but the EC is in charge of charge control.

The tps65090 interupt line is routed to both the AP and the EC, which
can cause quite a headache.  Having two people adjusting masks and
acking interrupts is a recipe for disaster.

In the shipping kernel we had a hack to have the AP pay attention to
the IRQ but not to ack it.  It also wasn't supposed to configure the
IRQ in any way.  That hack allowed us to detect when the device was
charging without messing with the EC's state.

The current tps65090 infrastructure makes the above difficult, and it
was a bit of a hack to begin with.  Rather than uglify the driver to
support it, just extend the driver's existing notion of "no irq" to
the charger.  This makes the charger code poll every 2 seconds for AC
detect, which is sufficient.

For proper functioning, requires (mfd: tps65090: Don't tell child
devices we have an IRQ if we don't).  If we don't have that patch
we'll simply fail to probe on devices without an interrupt (just like
we did before this patch).

Signed-off-by: Doug Anderson <dianders@chromium.org>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
[sre@kernel.org: Use -ENXIO instead of NO_IRQ for missing interrupt,
since NO_IRQ is not available on all architectures.]
Signed-off-by: Sebastian Reichel <sre@kernel.org>

1 files changed, 59 insertions, 17 deletions

diff --git a/drivers/power/tps65090-charger.c b/drivers/power/tps65090-charger.c
index 1685f63b9e5d..3e8ba97c8169 100644
--- a/drivers/power/tps65090-charger.c
+++ b/drivers/power/tps65090-charger.c
@@ -17,9 +17,11 @@
  */
 #include <linux/delay.h>
 #include <linux/err.h>
+#include <linux/freezer.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
+#include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
@@ -32,11 +34,15 @@
 #define TPS65090_VACG           BIT(1)
 #define TPS65090_NOITERM        BIT(5)
 
+#define POLL_INTERVAL           (HZ * 2)        /* Used when no irq */
+
 struct tps65090_charger {
         struct  device  *dev;
         int     ac_online;
         int     prev_ac_online;
         int     irq;
+        struct task_struct      *poll_task;
+        bool                    passive_mode;
         struct power_supply     ac;
         struct tps65090_platform_data *pdata;
 };
@@ -49,6 +55,9 @@ static int tps65090_low_chrg_current(struct tps65090_charger *charger)
 {
         int ret;
 
+        if (charger->passive_mode)
+                return 0;
+
         ret = tps65090_write(charger->dev->parent, TPS65090_REG_CG_CTRL5,
                         TPS65090_NOITERM);
         if (ret < 0) {
@@ -64,6 +73,9 @@ static int tps65090_enable_charging(struct tps65090_charger *charger)
         int ret;
         uint8_t ctrl0 = 0;
 
+        if (charger->passive_mode)
+                return 0;
+
         ret = tps65090_read(charger->dev->parent, TPS65090_REG_CG_CTRL0,
                             &ctrl0);
         if (ret < 0) {
@@ -87,6 +99,9 @@ static int tps65090_config_charger(struct tps65090_charger *charger)
         uint8_t intrmask = 0;
         int ret;
 
+        if (charger->passive_mode)
+                return 0;
+
         if (charger->pdata->enable_low_current_chrg) {
                 ret = tps65090_low_chrg_current(charger);
                 if (ret < 0) {
@@ -164,10 +179,14 @@ static irqreturn_t tps65090_charger_isr(int irq, void *dev_id)
         }
 
         /* Clear interrupts. */
-        ret = tps65090_write(charger->dev->parent, TPS65090_REG_INTR_STS, 0x00);
-        if (ret < 0) {
-                dev_err(charger->dev, "%s(): Error in writing reg 0x%x\n",
+        if (!charger->passive_mode) {
+                ret = tps65090_write(charger->dev->parent,
+                                     TPS65090_REG_INTR_STS, 0x00);
+                if (ret < 0) {
+                        dev_err(charger->dev,
+                                "%s(): Error in writing reg 0x%x\n",
                                 __func__, TPS65090_REG_INTR_STS);
+                }
         }
 
         if (charger->prev_ac_online != charger->ac_online)
@@ -198,6 +217,18 @@ static struct tps65090_platform_data *
 
 }
 
+static int tps65090_charger_poll_task(void *data)
+{
+        set_freezable();
+
+        while (!kthread_should_stop()) {
+                schedule_timeout_interruptible(POLL_INTERVAL);
+                try_to_freeze();
+                tps65090_charger_isr(-1, data);
+        }
+        return 0;
+}
+
 static int tps65090_charger_probe(struct platform_device *pdev)
 {
         struct tps65090_charger *cdata;
@@ -244,22 +275,10 @@ static int tps65090_charger_probe(struct platform_device *pdev)
         }
 
         irq = platform_get_irq(pdev, 0);
-        if (irq <= 0) {
-                dev_warn(&pdev->dev, "Unable to get charger irq = %d\n", irq);
-                ret = irq;
-                goto fail_unregister_supply;
-        }
-
+        if (irq < 0)
+                irq = -ENXIO;
         cdata->irq = irq;
 
-        ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
-                tps65090_charger_isr, 0, "tps65090-charger", cdata);
-        if (ret) {
-                dev_err(cdata->dev, "Unable to register irq %d err %d\n", irq,
-                        ret);
-                goto fail_unregister_supply;
-        }
-
         ret = tps65090_config_charger(cdata);
         if (ret < 0) {
                 dev_err(&pdev->dev, "charger config failed, err %d\n", ret);
@@ -285,6 +304,27 @@ static int tps65090_charger_probe(struct platform_device *pdev)
                 power_supply_changed(&cdata->ac);
         }
 
+        if (irq != -ENXIO) {
+                ret = devm_request_threaded_irq(&pdev->dev, irq, NULL,
+                        tps65090_charger_isr, 0, "tps65090-charger", cdata);
+                if (ret) {
+                        dev_err(cdata->dev,
+                                "Unable to register irq %d err %d\n", irq,
+                                ret);
+                        goto fail_unregister_supply;
+                }
+        } else {
+                cdata->poll_task = kthread_run(tps65090_charger_poll_task,
+                                              cdata, "ktps65090charger");
+                cdata->passive_mode = true;
+                if (IS_ERR(cdata->poll_task)) {
+                        ret = PTR_ERR(cdata->poll_task);
+                        dev_err(cdata->dev,
+                                "Unable to run kthread err %d\n", ret);
+                        goto fail_unregister_supply;
+                }
+        }
+
         return 0;
 
 fail_unregister_supply:
@@ -297,6 +337,8 @@ static int tps65090_charger_remove(struct platform_device *pdev)
 {
         struct tps65090_charger *cdata = platform_get_drvdata(pdev);
 
+        if (cdata->irq == -ENXIO)
+                kthread_stop(cdata->poll_task);
         power_supply_unregister(&cdata->ac);
 
         return 0;