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twl4030_charger: add software controlled linear charging mode. 

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

Linear charging does a good job with not-so-reliable power sources.
Auto mode does not work well as it switches off when voltage drops
momentarily.  Care must be taken not to over-charge.

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.

Original-by: Andreas Kemnade <andreas@kemnade.info>
Signed-off-by: NeilBrown <neil@brown.name>
Signed-off-by: Sebastian Reichel <sre@kernel.org>
hifive-unleashed-5.1
NeilBrown 2015-07-30 10:11:24 +10:00 committed by Sebastian Reichel
parent 22d4c33f73
commit 7f4a633d21
2 changed files with 59 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/ABI/testing/sysfs-class-power-twl4030
View File

@ -24,3 +24,12 @@ Description:
"auto" - draw power as appropriate for detected
power source and battery status.
"off" - do not draw any power.
"continuous"
- activate mode described as "linear" in
TWL data sheets. This uses whatever
current is available and doesn't switch off
when voltage drops.
This is useful for unstable power sources
such as bicycle dynamo, but care should
be taken that battery is not over-charged.

55
drivers/power/twl4030_charger.c
View File

@ -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)
@ -112,12 +117,13 @@ struct twl4030_bci {
int usb_mode; /* charging mode requested */
#define CHARGE_OFF 0
#define CHARGE_AUTO 1
#define CHARGE_LINEAR 2
unsigned long event;
};
/* strings for 'usb_mode' values */
static char *modes[] = { "off", "auto" };
static char *modes[] = { "off", "auto", "continuous" };
/*
* clear and set bits on an given register on a given module
@ -404,16 +410,42 @@ 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);
/* 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);
@ -652,6 +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);
@ -750,6 +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->desc->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) {
case POWER_SUPPLY_PROP_STATUS: