gpadc: optimize driver initialization

ADC trimming cost a long time. It blocks the kernel boot sequence.
Change to do trimming in a single workqueue.

Change-Id: Icd3232fb40d13e1b0c3d544840d2a975fe005d6e
Signed-off-by: Bin Yang <bin.yang@intel.com>

diff --git a/drivers/hwmon/intel_mid_gpadc.c b/drivers/hwmon/intel_mid_gpadc.c
index 652459f..acaeef2 100644 (file)
--- a/drivers/hwmon/intel_mid_gpadc.c
+++ b/drivers/hwmon/intel_mid_gpadc.c
@@ -33,6 +33,7 @@
 #include <linux/sched.h>
 #include <linux/platform_device.h>
 #include <linux/pm_qos_params.h>
+#include <linux/workqueue.h>
 #include <asm/intel_scu_ipc.h>
 #include <asm/intel_mid_gpadc.h>
 
@@ -83,6 +84,12 @@
 
 struct gpadc_info {
        int initialized;
+
+       struct workqueue_struct *workq;
+       wait_queue_head_t trimming_wait;
+       struct work_struct trimming_work;
+       int trimming_start;
+
        /* This mutex protects gpadc sample/config from concurrent conflict.
           Any function, which does the sample or config, needs to
           hold this lock.
@@ -158,11 +165,20 @@ static int gpadc_poweroff(struct gpadc_info *mgi)
        return 0;
 }
 
-static void gpadc_trimming(struct gpadc_info *mgi)
+static void gpadc_trimming(struct work_struct *work)
 {
        u8 data;
        int fse, zse, fse_sign, zse_sign;
+       struct gpadc_info *mgi =
+               container_of(work, struct gpadc_info, trimming_work);
 
+       mutex_lock(&mgi->lock);
+       mgi->trimming_start = 1;
+       wake_up(&mgi->trimming_wait);
+       if (gpadc_poweron(mgi, 1)) {
+               dev_err(mgi->dev, "power on failed\n");
+               goto failed;
+       }
        /* calibration */
        gpadc_read(ADC1CNTL1, &data);
        data &= ~ADC1CNTL1_AD1OFFSETEN;
@@ -197,6 +213,13 @@ static void gpadc_trimming(struct gpadc_info *mgi)
        zse += data & 0x3;
        mgi->izse = zse;
        mgi->ige = fse + zse;
+       if (gpadc_poweroff(mgi)) {
+               dev_err(mgi->dev, "power off failed\n");
+               goto failed;
+       }
+
+failed:
+       mutex_unlock(&mgi->lock);
 }
 
 static irqreturn_t msic_gpadc_isr(int irq, void *data)
@@ -505,6 +528,10 @@ static int __devinit msic_gpadc_probe(struct platform_device *pdev)
 
        mutex_init(&mgi->lock);
        init_waitqueue_head(&mgi->wait);
+       init_waitqueue_head(&mgi->trimming_wait);
+       mgi->workq = create_singlethread_workqueue(dev_name(&pdev->dev));
+       if (mgi->workq == NULL)
+               return -ENOMEM;
 
        mgi->dev = &pdev->dev;
        mgi->intr = ioremap_nocache(pdata->intr, 4);
@@ -518,14 +545,10 @@ static int __devinit msic_gpadc_probe(struct platform_device *pdev)
                goto err_exit;
        }
 
-       err = gpadc_poweron(mgi, 1);
-       if (err)
-               goto err_exit;
        gpadc_write(ADC1ADDR0, MSIC_STOPCH);
-       gpadc_trimming(mgi);
-       err = gpadc_poweroff(mgi);
-       if (err)
-               goto err_exit;
+       INIT_WORK(&mgi->trimming_work, gpadc_trimming);
+       queue_work(mgi->workq, &mgi->trimming_work);
+       wait_event(mgi->trimming_wait, mgi->trimming_start);
        mgi->initialized = 1;
 
        return 0;
@@ -541,6 +564,8 @@ static int __devexit msic_gpadc_remove(struct platform_device *pdev)
 
        free_irq(mgi->irq, mgi);
        iounmap(mgi->intr);
+       flush_workqueue(mgi->workq);
+       destroy_workqueue(mgi->workq);
        return 0;
 }