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ARM: mxs: Document the power block initialization

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This patch adds documentation for the functions used during the
initialization of MXS power block.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
master
Marek Vasut 12 years ago committed by Stefano Babic
parent 2f9c8ee079
commit d4c9135c96
1 changed files with 209 additions and 0 deletions
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  1. 209
      arch/arm/cpu/arm926ejs/mxs/spl_power_init.c

209
arch/arm/cpu/arm926ejs/mxs/spl_power_init.c
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@ -14,6 +14,13 @@
#include "mxs_init.h"
/**
* mxs_power_clock2xtal() - Switch CPU core clock source to 24MHz XTAL
*
* This function switches the CPU core clock from PLL to 24MHz XTAL
* oscilator. This is necessary if the PLL is being reconfigured to
* prevent crash of the CPU core.
*/
static void mxs_power_clock2xtal(void)
{
struct mxs_clkctrl_regs *clkctrl_regs =
@ -24,6 +31,13 @@ static void mxs_power_clock2xtal(void)
&clkctrl_regs->hw_clkctrl_clkseq_set);
}
/**
* mxs_power_clock2pll() - Switch CPU core clock source to PLL
*
* This function switches the CPU core clock from 24MHz XTAL oscilator
* to PLL. This can only be called once the PLL has re-locked and once
* the PLL is stable after reconfiguration.
*/
static void mxs_power_clock2pll(void)
{
struct mxs_clkctrl_regs *clkctrl_regs =
@ -36,6 +50,13 @@ static void mxs_power_clock2pll(void)
CLKCTRL_CLKSEQ_BYPASS_CPU);
}
/**
* mxs_power_set_auto_restart() - Set the auto-restart bit
*
* This function ungates the RTC block and sets the AUTO_RESTART
* bit to work around a design bug on MX28EVK Rev. A .
*/
static void mxs_power_set_auto_restart(void)
{
struct mxs_rtc_regs *rtc_regs =
@ -66,6 +87,14 @@ static void mxs_power_set_auto_restart(void)
;
}
/**
* mxs_power_set_linreg() - Set linear regulators 25mV below DC-DC converter
*
* This function configures the VDDIO, VDDA and VDDD linear regulators output
* to be 25mV below the VDDIO, VDDA and VDDD output from the DC-DC switching
* converter. This is the recommended setting for the case where we use both
* linear regulators and DC-DC converter to power the VDDIO rail.
*/
static void mxs_power_set_linreg(void)
{
struct mxs_power_regs *power_regs =
@ -85,6 +114,11 @@ static void mxs_power_set_linreg(void)
POWER_VDDIOCTRL_LINREG_OFFSET_1STEPS_BELOW);
}
/**
* mxs_get_batt_volt() - Measure battery input voltage
*
* This function retrieves the battery input voltage and returns it.
*/
static int mxs_get_batt_volt(void)
{
struct mxs_power_regs *power_regs =
@ -96,11 +130,24 @@ static int mxs_get_batt_volt(void)
return volt;
}
/**
* mxs_is_batt_ready() - Test if the battery provides enough voltage to boot
*
* This function checks if the battery input voltage is higher than 3.6V and
* therefore allows the system to successfully boot using this power source.
*/
static int mxs_is_batt_ready(void)
{
return (mxs_get_batt_volt() >= 3600);
}
/**
* mxs_is_batt_good() - Test if battery is operational at all
*
* This function starts recharging the battery and tests if the input current
* provided by the 5V input recharging the battery is also sufficient to power
* the DC-DC converter.
*/
static int mxs_is_batt_good(void)
{
struct mxs_power_regs *power_regs =
@ -141,6 +188,15 @@ static int mxs_is_batt_good(void)
return 0;
}
/**
* mxs_power_setup_5v_detect() - Start the 5V input detection comparator
*
* This function enables the 5V detection comparator and sets the 5V valid
* threshold to 4.4V . We use 4.4V threshold here to make sure that even
* under high load, the voltage drop on the 5V input won't be so critical
* to cause undervolt on the 4P2 linear regulator supplying the DC-DC
* converter and thus making the system crash.
*/
static void mxs_power_setup_5v_detect(void)
{
struct mxs_power_regs *power_regs =
@ -153,6 +209,12 @@ static void mxs_power_setup_5v_detect(void)
POWER_5VCTRL_PWRUP_VBUS_CMPS);
}
/**
* mxs_src_power_init() - Preconfigure the power block
*
* This function configures reasonable values for the DC-DC control loop
* and battery monitor.
*/
static void mxs_src_power_init(void)
{
struct mxs_power_regs *power_regs =
@ -184,6 +246,12 @@ static void mxs_src_power_init(void)
clrbits_le32(&power_regs->hw_power_5vctrl, POWER_5VCTRL_DCDC_XFER);
}
/**
* mxs_power_init_4p2_params() - Configure the parameters of the 4P2 regulator
*
* This function configures the necessary parameters for the 4P2 linear
* regulator to supply the DC-DC converter from 5V input.
*/
static void mxs_power_init_4p2_params(void)
{
struct mxs_power_regs *power_regs =
@ -208,6 +276,12 @@ static void mxs_power_init_4p2_params(void)
0x3f << POWER_5VCTRL_CHARGE_4P2_ILIMIT_OFFSET);
}
/**
* mxs_enable_4p2_dcdc_input() - Enable or disable the DCDC input from 4P2
* @xfer: Select if the input shall be enabled or disabled
*
* This function enables or disables the 4P2 input into the DC-DC converter.
*/
static void mxs_enable_4p2_dcdc_input(int xfer)
{
struct mxs_power_regs *power_regs =
@ -304,6 +378,12 @@ static void mxs_enable_4p2_dcdc_input(int xfer)
POWER_CTRL_ENIRQ_VDD5V_DROOP);
}
/**
* mxs_power_init_4p2_regulator() - Start the 4P2 regulator
*
* This function enables the 4P2 regulator and switches the DC-DC converter
* to use the 4P2 input.
*/
static void mxs_power_init_4p2_regulator(void)
{
struct mxs_power_regs *power_regs =
@ -388,6 +468,12 @@ static void mxs_power_init_4p2_regulator(void)
writel(POWER_CTRL_DCDC4P2_BO_IRQ, &power_regs->hw_power_ctrl_clr);
}
/**
* mxs_power_init_dcdc_4p2_source() - Switch DC-DC converter to 4P2 source
*
* This function configures the DC-DC converter to be supplied from the 4P2
* linear regulator.
*/
static void mxs_power_init_dcdc_4p2_source(void)
{
struct mxs_power_regs *power_regs =
@ -410,6 +496,12 @@ static void mxs_power_init_dcdc_4p2_source(void)
}
}
/**
* mxs_power_enable_4p2() - Power up the 4P2 regulator
*
* This function drives the process of powering up the 4P2 linear regulator
* and switching the DC-DC converter input over to the 4P2 linear regulator.
*/
static void mxs_power_enable_4p2(void)
{
struct mxs_power_regs *power_regs =
@ -469,6 +561,14 @@ static void mxs_power_enable_4p2(void)
&power_regs->hw_power_charge_clr);
}
/**
* mxs_boot_valid_5v() - Boot from 5V supply
*
* This function configures the power block to boot from valid 5V input.
* This is called only if the 5V is reliable and can properly supply the
* CPU. This function proceeds to configure the 4P2 converter to be supplied
* from the 5V input.
*/
static void mxs_boot_valid_5v(void)
{
struct mxs_power_regs *power_regs =
@ -492,6 +592,11 @@ static void mxs_boot_valid_5v(void)
mxs_power_enable_4p2();
}
/**
* mxs_powerdown() - Shut down the system
*
* This function powers down the CPU completely.
*/
static void mxs_powerdown(void)
{
struct mxs_power_regs *power_regs =
@ -501,6 +606,12 @@ static void mxs_powerdown(void)
&power_regs->hw_power_reset);
}
/**
* mxs_batt_boot() - Configure the power block to boot from battery input
*
* This function configures the power block to boot from the battery voltage
* supply.
*/
static void mxs_batt_boot(void)
{
struct mxs_power_regs *power_regs =
@ -545,6 +656,14 @@ static void mxs_batt_boot(void)
0x8 << POWER_5VCTRL_CHARGE_4P2_ILIMIT_OFFSET);
}
/**
* mxs_handle_5v_conflict() - Test if the 5V input is reliable
*
* This function tests if the 5V input can reliably supply the system. If it
* can, then proceed to configuring the system to boot from 5V source, otherwise
* try booting from battery supply. If we can not boot from battery supply
* either, shut down the system.
*/
static void mxs_handle_5v_conflict(void)
{
struct mxs_power_regs *power_regs =
@ -581,6 +700,12 @@ static void mxs_handle_5v_conflict(void)
}
}
/**
* mxs_5v_boot() - Configure the power block to boot from 5V input
*
* This function handles configuration of the power block when supplied by
* a 5V input.
*/
static void mxs_5v_boot(void)
{
struct mxs_power_regs *power_regs =
@ -604,6 +729,12 @@ static void mxs_5v_boot(void)
mxs_handle_5v_conflict();
}
/**
* mxs_init_batt_bo() - Configure battery brownout threshold
*
* This function configures the battery input brownout threshold. The value
* at which the battery brownout happens is configured to 3.0V in the code.
*/
static void mxs_init_batt_bo(void)
{
struct mxs_power_regs *power_regs =
@ -618,6 +749,12 @@ static void mxs_init_batt_bo(void)
writel(POWER_CTRL_ENIRQ_BATT_BO, &power_regs->hw_power_ctrl_clr);
}
/**
* mxs_switch_vddd_to_dcdc_source() - Switch VDDD rail to DC-DC converter
*
* This function turns off the VDDD linear regulator and therefore makes
* the VDDD rail be supplied only by the DC-DC converter.
*/
static void mxs_switch_vddd_to_dcdc_source(void)
{
struct mxs_power_regs *power_regs =
@ -632,6 +769,15 @@ static void mxs_switch_vddd_to_dcdc_source(void)
POWER_VDDDCTRL_DISABLE_STEPPING);
}
/**
* mxs_power_configure_power_source() - Configure power block source
*
* This function is the core of the power configuration logic. The function
* selects the power block input source and configures the whole power block
* accordingly. After the configuration is complete and the system is stable
* again, the function switches the CPU clock source back to PLL. Finally,
* the function switches the voltage rails to DC-DC converter.
*/
static void mxs_power_configure_power_source(void)
{
int batt_ready, batt_good;
@ -676,6 +822,15 @@ static void mxs_power_configure_power_source(void)
#endif
}
/**
* mxs_enable_output_rail_protection() - Enable power rail protection
*
* This function enables overload protection on the power rails. This is
* triggered if the power rails' voltage drops rapidly due to overload and
* in such case, the supply to the powerrail is cut-off, protecting the
* CPU from damage. Note that under such condition, the system will likely
* crash or misbehave.
*/
static void mxs_enable_output_rail_protection(void)
{
struct mxs_power_regs *power_regs =
@ -694,6 +849,13 @@ static void mxs_enable_output_rail_protection(void)
POWER_VDDIOCTRL_PWDN_BRNOUT);
}
/**
* mxs_get_vddio_power_source_off() - Get VDDIO rail power source
*
* This function tests if the VDDIO rail is supplied by linear regulator
* or by the DC-DC converter. Returns 1 if powered by linear regulator,
* returns 0 if powered by the DC-DC converter.
*/
static int mxs_get_vddio_power_source_off(void)
{
struct mxs_power_regs *power_regs =
@ -722,6 +884,13 @@ static int mxs_get_vddio_power_source_off(void)
}
/**
* mxs_get_vddd_power_source_off() - Get VDDD rail power source
*
* This function tests if the VDDD rail is supplied by linear regulator
* or by the DC-DC converter. Returns 1 if powered by linear regulator,
* returns 0 if powered by the DC-DC converter.
*/
static int mxs_get_vddd_power_source_off(void)
{
struct mxs_power_regs *power_regs =
@ -810,6 +979,18 @@ static const struct mxs_vddx_cfg mxs_vddmem_cfg = {
};
#endif
/**
* mxs_power_set_vddx() - Configure voltage on DC-DC converter rail
* @cfg: Configuration data of the DC-DC converter rail
* @new_target: New target voltage of the DC-DC converter rail
* @new_brownout: New brownout trigger voltage
*
* This function configures the output voltage on the DC-DC converter rail.
* The rail is selected by the @cfg argument. The new voltage target is
* selected by the @new_target and the voltage is specified in mV. The
* new brownout value is selected by the @new_brownout argument and the
* value is also in mV.
*/
static void mxs_power_set_vddx(const struct mxs_vddx_cfg *cfg,
uint32_t new_target, uint32_t new_brownout)
{
@ -883,6 +1064,14 @@ static void mxs_power_set_vddx(const struct mxs_vddx_cfg *cfg,
}
}
/**
* mxs_setup_batt_detect() - Start the battery voltage measurement logic
*
* This function starts and configures the LRADC block. This allows the
* power initialization code to measure battery voltage and based on this
* knowledge, decide whether to boot at all, boot from battery or boot
* from 5V input.
*/
static void mxs_setup_batt_detect(void)
{
mxs_lradc_init();
@ -890,6 +1079,14 @@ static void mxs_setup_batt_detect(void)
early_delay(10);
}
/**
* mxs_ungate_power() - Ungate the POWER block
*
* This function ungates clock to the power block. In case the power block
* was still gated at this point, it will not be possible to configure the
* block and therefore the power initialization would fail. This function
* is only needed on i.MX233, on i.MX28 the power block is always ungated.
*/
static void mxs_ungate_power(void)
{
#ifdef CONFIG_MX23
@ -900,6 +1097,12 @@ static void mxs_ungate_power(void)
#endif
}
/**
* mxs_power_init() - The power block init main function
*
* This function calls all the power block initialization functions in
* proper sequence to start the power block.
*/
void mxs_power_init(void)
{
struct mxs_power_regs *power_regs =
@ -933,6 +1136,12 @@ void mxs_power_init(void)
}
#ifdef CONFIG_SPL_MXS_PSWITCH_WAIT
/**
* mxs_power_wait_pswitch() - Wait for power switch to be pressed
*
* This function waits until the power-switch was pressed to start booting
* the board.
*/
void mxs_power_wait_pswitch(void)
{
struct mxs_power_regs *power_regs =

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