All OLPC ECs are able to turn the power to the DCON on an off. Use the
regulator framework to expose the functionality.

Signed-off-by: Lubomir Rintel <lkund...@v3.sk>

---
Changes since v1:
- Use idiomatic form of return on error
- Avoid mixing bool and int

 drivers/platform/olpc/Kconfig   |  1 +
 drivers/platform/olpc/olpc-ec.c | 67 +++++++++++++++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/drivers/platform/olpc/Kconfig b/drivers/platform/olpc/Kconfig
index 7c643d24ad0f..c5a872fb286f 100644
--- a/drivers/platform/olpc/Kconfig
+++ b/drivers/platform/olpc/Kconfig
@@ -6,6 +6,7 @@ config OLPC
        select OF
        select OF_PROMTREE if X86
        select IRQ_DOMAIN
+       select REGULATOR
        help
          Add support for detecting the unique features of the OLPC
          XO hardware.
diff --git a/drivers/platform/olpc/olpc-ec.c b/drivers/platform/olpc/olpc-ec.c
index 2b80174b8f4b..f725ab2a2db9 100644
--- a/drivers/platform/olpc/olpc-ec.c
+++ b/drivers/platform/olpc/olpc-ec.c
@@ -14,6 +14,7 @@
 #include <linux/workqueue.h>
 #include <linux/module.h>
 #include <linux/list.h>
+#include <linux/regulator/driver.h>
 #include <linux/olpc-ec.h>
 
 struct ec_cmd_desc {
@@ -34,6 +35,10 @@ struct olpc_ec_priv {
        struct work_struct worker;
        struct mutex cmd_lock;
 
+       /* DCON regulator */
+       struct regulator_dev *dcon_rdev;
+       bool dcon_enabled;
+
        /* Pending EC commands */
        struct list_head cmd_q;
        spinlock_t cmd_q_lock;
@@ -344,9 +349,61 @@ static struct dentry *olpc_ec_setup_debugfs(void)
 
 #endif /* CONFIG_DEBUG_FS */
 
+static int olpc_ec_set_dcon_power(struct olpc_ec_priv *ec, bool state)
+{
+       unsigned char ec_byte = state;
+       int ret;
+
+       if (ec->dcon_enabled == state)
+               return 0;
+
+       ret = olpc_ec_cmd(EC_DCON_POWER_MODE, &ec_byte, 1, NULL, 0);
+       if (ret)
+               return ret;
+
+       ec->dcon_enabled = state;
+       return 0;
+}
+
+static int dcon_regulator_enable(struct regulator_dev *rdev)
+{
+       struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
+
+       return olpc_ec_set_dcon_power(ec, true);
+}
+
+static int dcon_regulator_disable(struct regulator_dev *rdev)
+{
+       struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
+
+       return olpc_ec_set_dcon_power(ec, false);
+}
+
+static int dcon_regulator_is_enabled(struct regulator_dev *rdev)
+{
+       struct olpc_ec_priv *ec = rdev_get_drvdata(rdev);
+
+       return ec->dcon_enabled ? 1 : 0;
+}
+
+static struct regulator_ops dcon_regulator_ops = {
+       .enable         = dcon_regulator_enable,
+       .disable        = dcon_regulator_disable,
+       .is_enabled     = dcon_regulator_is_enabled,
+};
+
+static const struct regulator_desc dcon_desc = {
+       .name   = "dcon",
+       .id     = 0,
+       .ops    = &dcon_regulator_ops,
+       .type   = REGULATOR_VOLTAGE,
+       .owner  = THIS_MODULE,
+};
+
 static int olpc_ec_probe(struct platform_device *pdev)
 {
        struct olpc_ec_priv *ec;
+       struct regulator_config config = { };
        int err;
 
        if (!ec_driver)
@@ -374,6 +431,16 @@ static int olpc_ec_probe(struct platform_device *pdev)
                return err;
        }
 
+       config.dev = pdev->dev.parent;
+       config.driver_data = ec;
+       ec->dcon_enabled = true;
+       ec->dcon_rdev = devm_regulator_register(&pdev->dev, &dcon_desc,
+                                                               &config);
+       if (IS_ERR(ec->dcon_rdev)) {
+               dev_err(&pdev->dev, "failed to register DCON regulator\n");
+               return PTR_ERR(ec->dcon_rdev);
+       }
+
        ec->dbgfs_dir = olpc_ec_setup_debugfs();
 
        return err;
-- 
2.19.1

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