[PATCH 12/15] twl4030_charger: add software controlled linear charging mode.

NeilBrown
2015-02-24T20:57:27Z

Add a 'continuous' option for usb charging which enabled
the "linear" charging mode of the twl4030.

Linear charging does a good job with not so reliable power sources, since
several voltage controlling is then often too intelligent.
It was used with a bike hub dynamo since a year or so. In that case there
are automatically charging stops when the cyclist needs a break.

Orignal-by: Andreas Kemnade <andreas@kemnade.info>
Signed-off-by: NeilBrown <neilb@suse.de>
---
drivers/power/twl4030_charger.c | 57 ++++++++++++++++++++++++++++++++++++---
1 file changed, 52 insertions(+), 5 deletions(-)

diff --git a/drivers/power/twl4030_charger.c b/drivers/power/twl4030_charger.c
index 19e8dbb1303e..6c53f0b601a4 100644
--- a/drivers/power/twl4030_charger.c
+++ b/drivers/power/twl4030_charger.c
@@ -24,6 +24,8 @@
#include <linux/usb/otg.h>
#include <linux/i2c/twl4030-madc.h>

+#define TWL4030_BCIMDEN 0x00
+#define TWL4030_BCIMDKEY 0x01
#define TWL4030_BCIMSTATEC 0x02
#define TWL4030_BCIICHG 0x08
#define TWL4030_BCIVAC 0x0a
@@ -35,13 +37,16 @@
#define TWL4030_BCIIREF1 0x27
#define TWL4030_BCIIREF2 0x28
#define TWL4030_BCIMFKEY 0x11
+#define TWL4030_BCIMFEN3 0x14
#define TWL4030_BCIMFTH8 0x1d
#define TWL4030_BCIMFTH9 0x1e
+#define TWL4030_BCIWDKEY 0x21

#define TWL4030_BCIMFSTS1 0x01

#define TWL4030_BCIAUTOWEN BIT(5)
#define TWL4030_CONFIG_DONE BIT(4)
+#define TWL4030_CVENAC BIT(2)
#define TWL4030_BCIAUTOUSB BIT(1)
#define TWL4030_BCIAUTOAC BIT(0)
#define TWL4030_CGAIN BIT(5)
@@ -110,6 +115,7 @@ struct twl4030_bci {
int usb_mode; /* charging mode requested */
#define CHARGE_OFF 0
#define CHARGE_AUTO 1
+#define CHARGE_LINEAR 2

unsigned long event;
};
@@ -392,16 +398,44 @@ static int twl4030_charger_enable_usb(struct twl4030_bci *bci, bool enable)
bci->usb_enabled = 1;
}

- /* forcing the field BCIAUTOUSB (BOOT_BCI[1]) to 1 */
- ret = twl4030_clear_set_boot_bci(0, TWL4030_BCIAUTOUSB);
- if (ret < 0)
- return ret;
+ if (bci->usb_mode == CHARGE_AUTO) {
+ /* forcing the field BCIAUTOUSB (BOOT_BCI[1]) to 1 */
+ ret = twl4030_clear_set_boot_bci(0, TWL4030_BCIAUTOUSB);
+ twl4030_clear_set_boot_bci(0, TWL4030_BCIAUTOAC|TWL4030_CVENAC);
+ }

/* forcing USBFASTMCHG(BCIMFSTS4[2]) to 1 */
ret = twl4030_clear_set(TWL_MODULE_MAIN_CHARGE, 0,
TWL4030_USBFASTMCHG, TWL4030_BCIMFSTS4);
+ if (bci->usb_mode == CHARGE_LINEAR) {
+ twl4030_clear_set_boot_bci(TWL4030_BCIAUTOAC|TWL4030_CVENAC, 0);
+ /* Watch dog key: WOVF acknowledge */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x33,
+ TWL4030_BCIWDKEY);
+ /* 0x24 + EKEY6: off mode */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,
+ TWL4030_BCIMDKEY);
+ /* EKEY2: Linear charge: usb path */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x26,
+ TWL4030_BCIMDKEY);
+ /* WDKEY5: stop watchdog count */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf3,
+ TWL4030_BCIWDKEY);
+ /* enable MFEN3 access */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x9c,
+ TWL4030_BCIMFKEY);
+ /* ICHGEOCEN - end-of-charge monitor (current < 80mA)
+ * (charging continues)
+ * ICHGLOWEN - current level monitor (charge continues)
+ * don't monitor over-current or heat save
+ */
+ ret = twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0xf0,
+ TWL4030_BCIMFEN3);
+ }
} else {
ret = twl4030_clear_set_boot_bci(TWL4030_BCIAUTOUSB, 0);
+ ret |= twl_i2c_write_u8(TWL_MODULE_MAIN_CHARGE, 0x2a,
+ TWL4030_BCIMDKEY);
if (bci->usb_enabled) {
pm_runtime_mark_last_busy(bci->transceiver->dev);
pm_runtime_put_autosuspend(bci->transceiver->dev);
@@ -637,7 +671,7 @@ static int twl4030_bci_usb_ncb(struct notifier_block *nb, unsigned long val,
/*
* sysfs charger enabled store
*/
-static char *modes[] = { "off", "auto" };
+static char *modes[] = { "off", "auto", "continuous" };
static ssize_t
twl4030_bci_mode_store(struct device *dev, struct device_attribute *attr,
const char *buf, size_t n)
@@ -650,6 +684,8 @@ twl4030_bci_mode_store(struct device *dev, struct device_attribute *attr,
mode = 0;
else if (sysfs_streq(buf, modes[1]))
mode = 1;
+ else if (sysfs_streq(buf, modes[2]))
+ mode = 2;
else
return -EINVAL;
twl4030_charger_enable_usb(bci, false);
@@ -748,6 +784,17 @@ static int twl4030_bci_get_property(struct power_supply *psy,
is_charging = state & TWL4030_MSTATEC_USB;
else
is_charging = state & TWL4030_MSTATEC_AC;
+ if (!is_charging) {
+ u8 s;
+ twl4030_bci_read(TWL4030_BCIMDEN, &s);
+ if (psy->type == POWER_SUPPLY_TYPE_USB)
+ is_charging = s & 1;
+ else
+ is_charging = s & 2;
+ if (is_charging)
+ /* A little white lie */
+ state = TWL4030_MSTATEC_QUICK1;
+ }

switch (psp) {