mfd: Introduce remove_script function for twl4030

New function twl4030_remove_script(u8 flags) takes a script type as
defined in twl.h and prevents any script already loaded in that position
from running.  This is accomplished by programming SEQ_ADD_* to 0x3f,
the END_OF_SCRIPT value, where SEQ_ADD_* is determined by flags.

(Future) users of this function include OMAP board files for machines
facing a race condition between sleep and warm reset.

Signed-off-by: Mike Turquette <mturquette@ti.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>

drivers/mfd/twl4030-power.c

@@ -461,6 +461,56 @@ out:
 	return err;
 }
 
+int twl4030_remove_script(u8 flags)
+{
+	int err = 0;
+
+	err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, R_KEY_1,
+			R_PROTECT_KEY);
+	if (err) {
+		pr_err("twl4030: unable to unlock PROTECT_KEY\n");
+		return err;
+	}
+
+	err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, R_KEY_2,
+			R_PROTECT_KEY);
+	if (err) {
+		pr_err("twl4030: unable to unlock PROTECT_KEY\n");
+		return err;
+	}
+
+	if (flags & TWL4030_WRST_SCRIPT) {
+		err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, END_OF_SCRIPT,
+				R_SEQ_ADD_WARM);
+		if (err)
+			return err;
+	}
+	if (flags & TWL4030_WAKEUP12_SCRIPT) {
+		if (err)
+		err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, END_OF_SCRIPT,
+				R_SEQ_ADD_S2A12);
+			return err;
+	}
+	if (flags & TWL4030_WAKEUP3_SCRIPT) {
+		err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, END_OF_SCRIPT,
+				R_SEQ_ADD_S2A3);
+		if (err)
+			return err;
+	}
+	if (flags & TWL4030_SLEEP_SCRIPT) {
+		err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, END_OF_SCRIPT,
+				R_SEQ_ADD_A2S);
+		if (err)
+			return err;
+	}
+
+	err = twl_i2c_write_u8(TWL4030_MODULE_PM_MASTER, 0, R_PROTECT_KEY);
+	if (err)
+		pr_err("TWL4030 Unable to relock registers\n");
+
+	return err;
+}
+
 void __init twl4030_power_init(struct twl4030_power_data *twl4030_scripts)
 {
 	int err = 0;