intel_mid_powerbtn: use shared SRAM to read Powerbutton state

BZ: 8874

switch power button read access from IPC to shared SRAM to help
reduce latency introduced by IPC call.

Change-Id: I158b6ffa5cc28f7db527e0740fb1b54d40082cf0
Signed-off-by: Zhifeng Wang <zhifeng.wang@intel.com>
Reviewed-on: http://android.intel.com:8080/24607
Reviewed-by: Gross, Mark <mark.gross@intel.com>
Tested-by: Gross, Mark <mark.gross@intel.com>

diff --git a/drivers/platform/x86/intel_mid_powerbtn.c b/drivers/platform/x86/intel_mid_powerbtn.c
index f1ae507..46f9dbb 100644 (file)
--- a/drivers/platform/x86/intel_mid_powerbtn.c
+++ b/drivers/platform/x86/intel_mid_powerbtn.c
@@ -23,88 +23,127 @@
 #include <linux/slab.h>
 #include <linux/platform_device.h>
 #include <linux/input.h>
-
+#include <linux/io.h>
 #include <asm/intel_scu_ipc.h>
 
 #define DRIVER_NAME "msic_power_btn"
 
-#define MSIC_PB_STATUS 0x3f
-#define MSIC_PB_LEVEL  (1 << 3) /* 1 - release, 0 - press */
+/* SRAM address for power button state */
+#define MSIC_PB_STAT   0xffff7fd0
+  #define MSIC_PB_LEVEL (1 << 3) /* 1 - release, 0 - press */
+#define MSIC_PB_LEN    1
+
+/*
+ * MSIC document ti_datasheet defines the 1st bit reg 0x21 is used to mask
+ * power button interrupt
+ */
+#define MSIC_IRQLVL1MSK        0x21
+#define MSIC_PWRBTNM   (1 << 0)
+
+struct mfld_pb_priv {
+       struct input_dev *input;
+       int irq;
+       void __iomem *pb_stat;
+};
 
 static irqreturn_t mfld_pb_isr(int irq, void *dev_id)
 {
-       struct input_dev *input = dev_id;
-       int ret;
+       struct mfld_pb_priv *priv = dev_id;
        u8 pbstat;
 
-       ret = intel_scu_ipc_ioread8(MSIC_PB_STATUS, &pbstat);
-       if (ret < 0) {
-               dev_err(input->dev.parent, "Read error %d while reading"
-                              " MSIC_PB_STATUS\n", ret);
-       } else {
-               input_event(input, EV_KEY, KEY_POWER,
-                              !(pbstat & MSIC_PB_LEVEL));
-               input_sync(input);
-       }
+       pbstat = readb(priv->pb_stat);
+       dev_dbg(&priv->input->dev, "pbstat: 0x%x\n", pbstat);
+
+       input_event(priv->input, EV_KEY, KEY_POWER, !(pbstat & MSIC_PB_LEVEL));
+       input_sync(priv->input);
 
        return IRQ_HANDLED;
 }
 
 static int __devinit mfld_pb_probe(struct platform_device *pdev)
 {
+       struct mfld_pb_priv *priv;
        struct input_dev *input;
-       int irq = platform_get_irq(pdev, 0);
-       int error;
+       int ret;
+       int irq;
+       u8 value;
 
+       irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return -EINVAL;
 
+       priv = kzalloc(sizeof(struct mfld_pb_priv), GFP_KERNEL);
        input = input_allocate_device();
-       if (!input) {
-               dev_err(&pdev->dev, "Input device allocation error\n");
-               return -ENOMEM;
+       if (!priv || !input) {
+               ret = -ENOMEM;
+               goto fail;
        }
 
+       priv->input = input;
+       priv->irq = irq;
+       platform_set_drvdata(pdev, priv);
+
        input->name = pdev->name;
        input->phys = "power-button/input0";
-       input->id.bustype = BUS_HOST;
        input->dev.parent = &pdev->dev;
 
        input_set_capability(input, EV_KEY, KEY_POWER);
 
-       error = request_threaded_irq(irq, NULL, mfld_pb_isr, 0,
-                       DRIVER_NAME, input);
-       if (error) {
-               dev_err(&pdev->dev, "Unable to request irq %d for mfld power"
-                               "button\n", irq);
-               goto err_free_input;
+       priv->pb_stat = ioremap(MSIC_PB_STAT, MSIC_PB_LEN);
+       if (!priv->pb_stat) {
+               ret = -ENOMEM;
+               goto fail;
        }
 
-       error = input_register_device(input);
-       if (error) {
-               dev_err(&pdev->dev, "Unable to register input dev, error "
-                               "%d\n", error);
-               goto err_free_irq;
+       ret = request_irq(priv->irq, mfld_pb_isr,
+                         IRQF_NO_SUSPEND, DRIVER_NAME, priv);
+       if (ret) {
+               dev_err(&pdev->dev,
+                       "unable to request irq %d for power button\n", irq);
+               goto out_iounmap;
        }
 
-       platform_set_drvdata(pdev, input);
+       ret = input_register_device(input);
+       if (ret) {
+               dev_err(&pdev->dev,
+                       "unable to register input dev, error %d\n", ret);
+               goto out_free_irq;
+       }
+
+       /* SCU firmware might send power button interrupts to IA core before
+        * kernel boots and doesn't get EOI from IA core. The first bit of
+        * MSIC reg 0x21 is kept masked, and SCU firmware doesn't send new
+        * power interrupt to Android kernel. Unmask the bit when probing
+        * power button in kernel.
+        * There is a very narrow race between irq handler and power button
+        * initialization. The race happens rarely. So we needn't worry
+        * about it.
+        */
+       ret = intel_scu_ipc_ioread8(MSIC_IRQLVL1MSK, &value);
+       value &= ~MSIC_PWRBTNM;
+       ret = intel_scu_ipc_iowrite8(MSIC_IRQLVL1MSK, value);
+
        return 0;
 
-err_free_irq:
-       free_irq(irq, input);
-err_free_input:
+out_free_irq:
+       free_irq(priv->irq, priv);
+out_iounmap:
+       iounmap(priv->pb_stat);
+fail:
+       platform_set_drvdata(pdev, NULL);
        input_free_device(input);
-       return error;
+       kfree(priv);
+       return ret;
 }
 
 static int __devexit mfld_pb_remove(struct platform_device *pdev)
 {
-       struct input_dev *input = platform_get_drvdata(pdev);
-       int irq = platform_get_irq(pdev, 0);
+       struct mfld_pb_priv *priv = platform_get_drvdata(pdev);
 
-       free_irq(irq, input);
-       input_unregister_device(input);
-       platform_set_drvdata(pdev, NULL);
+       iounmap(priv->pb_stat);
+       free_irq(priv->irq, priv);
+       input_unregister_device(priv->input);
+       kfree(priv);
 
        return 0;
 }
@@ -114,23 +153,23 @@ static struct platform_driver mfld_pb_driver = {
                .name = DRIVER_NAME,
                .owner = THIS_MODULE,
        },
-       .probe  = mfld_pb_probe,
-       .remove = __devexit_p(mfld_pb_remove),
+       .probe  = mfld_pb_probe,
+       .remove = __devexit_p(mfld_pb_remove),
 };
 
 static int __init mfld_pb_init(void)
 {
        return platform_driver_register(&mfld_pb_driver);
 }
-module_init(mfld_pb_init);
 
 static void __exit mfld_pb_exit(void)
 {
        platform_driver_unregister(&mfld_pb_driver);
 }
+
+module_init(mfld_pb_init);
 module_exit(mfld_pb_exit);
 
 MODULE_AUTHOR("Hong Liu <hong.liu@intel.com>");
 MODULE_DESCRIPTION("Intel Medfield Power Button Driver");
 MODULE_LICENSE("GPL v2");
-MODULE_ALIAS("platform:" DRIVER_NAME);