[RFC,v15,02/11] ARM: qcom: Add Subsystem Power Manager (SPM) driver

Message ID 1425914206-22295-3-git-send-email-lina.iyer@linaro.org
State New
Headers show

Commit Message

Lina Iyer March 9, 2015, 3:16 p.m.
SPM is a hardware block that controls the peripheral logic surrounding
the application cores (cpu/l$). When the core executes WFI instruction,
the SPM takes over the putting the core in low power state as
configured. The wake up for the SPM is an interrupt at the GIC, which
then completes the rest of low power mode sequence and brings the core
out of low power mode.

The SPM has a set of control registers that configure the SPMs
individually based on the type of the core and the runtime conditions.
SPM is a finite state machine block to which a sequence is provided and
it interprets the bytes and executes them in sequence. Each low power
mode that the core can enter into is provided to the SPM as a sequence.

Configure the SPM to set the core (cpu or L2) into its low power mode,
the index of the first command in the sequence is set in the SPM_CTL
register. When the core executes ARM wfi instruction, it triggers the
SPM state machine to start executing from that index. The SPM state
machine waits until the interrupt occurs and starts executing the rest
of the sequence until it hits the end of the sequence. The end of the
sequence jumps the core out of its low power mode.

Add support for an idle driver to set up the SPM to place the core in
Standby or Standalone power collapse mode when the core is idle.

Based on work by: Mahesh Sivasubramanian <msivasub@codeaurora.org>,
Ai Li <ali@codeaurora.org>, Praveen Chidambaram <pchidamb@codeaurora.org>
Original tree available at -
git://codeaurora.org/quic/la/kernel/msm-3.10.git

Cc: Stephen Boyd <sboyd@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Kevin Hilman <khilman@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 .../devicetree/bindings/arm/msm/qcom,saw2.txt      |  31 +-
 drivers/soc/qcom/Kconfig                           |   7 +
 drivers/soc/qcom/Makefile                          |   1 +
 drivers/soc/qcom/spm.c                             | 422 +++++++++++++++++++++
 4 files changed, 455 insertions(+), 6 deletions(-)
 create mode 100644 drivers/soc/qcom/spm.c

Comments

Lina Iyer March 10, 2015, 6:51 p.m. | #1
On Tue, Mar 10 2015 at 11:26 -0600, Kumar Gala wrote:
>
>On Mar 9, 2015, at 10:16 AM, Lina Iyer <lina.iyer@linaro.org> wrote:
>
>> SPM is a hardware block that controls the peripheral logic surrounding
>> the application cores (cpu/l$). When the core executes WFI instruction,
>> the SPM takes over the putting the core in low power state as
>> configured. The wake up for the SPM is an interrupt at the GIC, which
>> then completes the rest of low power mode sequence and brings the core
>> out of low power mode.
>>
>> The SPM has a set of control registers that configure the SPMs
>> individually based on the type of the core and the runtime conditions.
>> SPM is a finite state machine block to which a sequence is provided and
>> it interprets the bytes and executes them in sequence. Each low power
>> mode that the core can enter into is provided to the SPM as a sequence.
>>
>> Configure the SPM to set the core (cpu or L2) into its low power mode,
>> the index of the first command in the sequence is set in the SPM_CTL
>> register. When the core executes ARM wfi instruction, it triggers the
>> SPM state machine to start executing from that index. The SPM state
>> machine waits until the interrupt occurs and starts executing the rest
>> of the sequence until it hits the end of the sequence. The end of the
>> sequence jumps the core out of its low power mode.
>>
>> Add support for an idle driver to set up the SPM to place the core in
>> Standby or Standalone power collapse mode when the core is idle.
>>
>> Based on work by: Mahesh Sivasubramanian <msivasub@codeaurora.org>,
>> Ai Li <ali@codeaurora.org>, Praveen Chidambaram <pchidamb@codeaurora.org>
>> Original tree available at -
>> git://codeaurora.org/quic/la/kernel/msm-3.10.git
>>
>> Cc: Stephen Boyd <sboyd@codeaurora.org>
>> Cc: Arnd Bergmann <arnd@arndb.de>
>> Cc: Kevin Hilman <khilman@linaro.org>
>> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
>> Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
>> ---
>> .../devicetree/bindings/arm/msm/qcom,saw2.txt      |  31 +-
>> drivers/soc/qcom/Kconfig                           |   7 +
>> drivers/soc/qcom/Makefile                          |   1 +
>> drivers/soc/qcom/spm.c                             | 422 +++++++++++++++++++++
>> 4 files changed, 455 insertions(+), 6 deletions(-)
>> create mode 100644 drivers/soc/qcom/spm.c
>>
>> diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
>> index 1505fb8..690c3c0 100644
>> --- a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
>> +++ b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
>> @@ -2,11 +2,20 @@ SPM AVS Wrapper 2 (SAW2)
>>
>> The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the
>> Adaptive Voltage Scaling (AVS) hardware. The SPM is a programmable
>> -micro-controller that transitions a piece of hardware (like a processor or
>> +power-controller that transitions a piece of hardware (like a processor or
>> subsystem) into and out of low power modes via a direct connection to
>> the PMIC. It can also be wired up to interact with other processors in the
>> system, notifying them when a low power state is entered or exited.
>>
>> +Multiple revisions of the SAW hardware are supported using these Device Nodes.
>> +SAW2 revisions differ in the register offset and configuration data. Also, the
>> +same revision of the SAW in different SoCs may have different configuration
>> +data due the the differences in hardware capabilities. Hence the SoC name, the
>> +version of the SAW hardware in that SoC and the distinction between cpu (big
>> +or Little) or cache, may be needed to uniquely identify the SAW register
>> +configuration and initialization data. The compatible string is used to
>> +indicate this parameter.
>> +
>> PROPERTIES
>>
>> - compatible:
>> @@ -14,10 +23,13 @@ PROPERTIES
>> 	Value type: <string>
>> 	Definition: shall contain "qcom,saw2". A more specific value should be
>> 		    one of:
>> -			 "qcom,saw2-v1"
>> -			 "qcom,saw2-v1.1"
>> -			 "qcom,saw2-v2"
>> -			 "qcom,saw2-v2.1"
>> +			"qcom,saw2-v1"
>> +			"qcom,saw2-v1.1"
>> +			"qcom,saw2-v2"
>> +			"qcom,saw2-v2.1"
>> +			"qcom,apq8064-saw2-v1.1-cpu"
>> +			"qcom,msm8974-saw2-v2.1-cpu"
>> +			"qcom,apq8084-saw2-v2.1-cpu”
>>
>
>We don’t seem to use the "qcom,saw2-v1*” variants so should we just drop them?

Sure. Will fix in the next.
>
>
>> - reg:
>> 	Usage: required
>> @@ -26,10 +38,17 @@ PROPERTIES
>> 		    the register region. An optional second element specifies
>> 		    the base address and size of the alias register region.
>>
>> +- regulator:
>> +	Usage: optional
>> +	Value type: boolean
>> +	Definition: Indicates that this SPM device acts as a regulator device
>> +			device for the core (CPU or Cache) the SPM is attached
>> +			to.
>>
>> Example:
>>
>> -	regulator@2099000 {
>> +	power-controller@2099000 {
>> 		compatible = "qcom,saw2";
>> 		reg = <0x02099000 0x1000>, <0x02009000 0x1000>;
>> +		regulator;
>> 	};
>
>- k
>
>-- 
>Qualcomm Innovation Center, Inc.
>The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
>a Linux Foundation Collaborative Project
>
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Lina Iyer March 12, 2015, 10:50 p.m. | #2
On Mon, Mar 09 2015 at 09:17 -0600, Lina Iyer wrote:

[...]

>+static int qcom_pm_collapse(unsigned long int unused)
>+{
>+	qcom_scm_cpu_power_down(QCOM_SCM_L2_ON);

Rebase against latest SCM patches. Change to QCOM_SCM_CPU_PWR_DOWN_L2_ON.
>+
>+	/*
>+	 * Returns here only if there was a pending interrupt and we did not
>+	 * power down as a result.
>+	 */
>+	return -1;
>+}
>+
>+static int qcom_cpu_standby(int cpuarg)
>+{
>+	spm_set_low_power_mode(PM_SLEEP_MODE_STBY);
>+	cpu_do_idle();
>+
>+	return 0;
>+}
>+
>+static int qcom_cpu_spc(int cpu)
>+{
>+	int ret;
>+
>+	spm_set_low_power_mode(PM_SLEEP_MODE_SPC);
>+	cpu_pm_enter();
Remove this. This is now done by cpuidle driver.

>+	ret = cpu_suspend(0, qcom_pm_collapse);
>+	/*
>+	 * ARM common code may execute WFI, and if the SPM mode is not reset,
>+	 * then we may accidently do power down state.
>+	 * SPM is configured to reset to do STBY, but that relies on the
>+	 * SPM state machine to be executed. When an interrupt is pending as we
>+	 * enter idle state, SPM would not execute its state machine, so the
>+	 * SPM may remain configured to do power down state.
>+	 * Reset the state back to standby.
>+	 */
>+	spm_set_low_power_mode(PM_SLEEP_MODE_STBY);
>+	cpu_pm_exit();
And this..

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Lina Iyer March 16, 2015, 10:51 p.m. | #3
On Mon, Mar 16 2015 at 15:51 -0600, Stephen Boyd wrote:
>On 03/09/15 08:16, Lina Iyer wrote:
>> +
>> +static int qcom_idle_enter(int cpu, unsigned long index)
>> +{
>> +	if (!per_cpu(qcom_idle_ops, cpu)[index])
>> +		return -EOPNOTSUPP;
>
>Is this case still happening?
>
I think, I can remove it safely now.
>> +
>> +	return per_cpu(qcom_idle_ops, cpu)[index](cpu);
>> +}
>> +
>> +const struct of_device_id qcom_idle_state_match[] __initconst = {
>
>static?
>
Ok

>> +	{ .compatible = "qcom,idle-state-stby", .data = qcom_cpu_standby },
>> +	{ .compatible = "qcom,idle-state-spc", .data = qcom_cpu_spc },
>> +	{ },
>> +};
>> +
>> +static int __init qcom_cpuidle_init(struct device_node *cpu_node, int cpu)
>> +{
>> +	const struct of_device_id *match_id;
>> +	struct device_node *state_node;
>> +	int i;
>> +	int state_count = 0;
>> +	idle_fn idle_fns[CPUIDLE_STATE_MAX];
>> +	idle_fn *fns;
>> +	cpumask_t mask;
>> +	bool use_scm_power_down = false;
>> +
>> +	for (i = 0; ; i++) {
>> +		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
>> +		if (!state_node)
>> +			break;
>> +
>> +		if (!of_device_is_available(state_node))
>> +			continue;
>> +
>> +		if (i == CPUIDLE_STATE_MAX) {
>> +			pr_warn("%s: cpuidle states reached max possible\n",
>> +					__func__);
>> +			break;
>> +		}
>> +
>> +		match_id = of_match_node(qcom_idle_state_match, state_node);
>> +		if (!match_id)
>> +			return -ENODEV;
>> +
>> +		idle_fns[state_count] = match_id->data;
>> +
>> +		/* Check if any of the states allow power down */
>> +		if (match_id->data == qcom_cpu_spc)
>> +			use_scm_power_down = true;
>> +
>> +		state_count++;
>> +	}
>> +
>> +	if (!state_count) {
>> +		pr_warn("No idle ops founds for cpu %d\n", cpu);
>
>Maybe pr_debug? It's not the end of the world that we don't have cpuidle.
>
Sure.

>> +		return -ENODEV;
>> +	}
>> +
>> +	fns = kcalloc(state_count, sizeof(*fns), GFP_KERNEL);
>> +	if (!fns)
>> +		return -ENOMEM;
>> +
>> +	for (i = 0; i < state_count; i++)
>> +		fns[i] = idle_fns[i];
>> +
>> +	if (use_scm_power_down) {
>> +		/* We have atlease one power down mode */
>
>s/atlease/at least/
>
Thanks!

>> +		cpumask_clear(&mask);
>> +		cpumask_set_cpu(cpu, &mask);
>> +		qcom_scm_set_warm_boot_addr(cpu_resume, &mask);
>> +	}
>> +
>> +	per_cpu(qcom_idle_ops, cpu) = fns;
>> +
>> +	/*
>> +	 * Condition: cpuidle_driver_register() needs to happen before
>> +	 * cpuidle_register_device().
>> +	 * Check if the SPM probe has happened -
>> +	 * - If SPM probed successfully before arm_idle_init(), then defer
>> +	 *   the registration of cpuidle_device back to arm_idle_init()
>> +	 * - If the SPM probe happens in the future, then let the SPM probe
>> +	 *   register the cpuidle device, return -ENOSYS.
>> +	 */
>> +	return per_cpu(cpu_spm_drv, cpu) ? 0 : -ENOSYS;
>> +}
>> +
>> +struct cpuidle_ops qcom_kpss_v1_cpuidle_ops __initdata = {
>> +	.name = "qcom,kpss-acc-v1",
>> +	.suspend = qcom_idle_enter,
>> +	.init = qcom_cpuidle_init,
>> +};
>> +
>> +struct cpuidle_ops qcom_kpss_v2_cpuidle_ops __initdata = {
>> +	.name = "qcom,kpss-acc-v2",
>> +	.suspend = qcom_idle_enter,
>> +	.init = qcom_cpuidle_init,
>> +};
>> +
>>
>
>This just looks weird because of the macro magic in Daniel's series. Any
>reason we can't use the linker instead of doing preprocessor magic so
>that it looks like these structures are actually used?
>
Hmm.. Will wait on Daniel's response to your other mail.

>-- 
>Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
>a Linux Foundation Collaborative Project
>
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Patch

diff --git a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
index 1505fb8..690c3c0 100644
--- a/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
+++ b/Documentation/devicetree/bindings/arm/msm/qcom,saw2.txt
@@ -2,11 +2,20 @@  SPM AVS Wrapper 2 (SAW2)
 
 The SAW2 is a wrapper around the Subsystem Power Manager (SPM) and the
 Adaptive Voltage Scaling (AVS) hardware. The SPM is a programmable
-micro-controller that transitions a piece of hardware (like a processor or
+power-controller that transitions a piece of hardware (like a processor or
 subsystem) into and out of low power modes via a direct connection to
 the PMIC. It can also be wired up to interact with other processors in the
 system, notifying them when a low power state is entered or exited.
 
+Multiple revisions of the SAW hardware are supported using these Device Nodes.
+SAW2 revisions differ in the register offset and configuration data. Also, the
+same revision of the SAW in different SoCs may have different configuration
+data due the the differences in hardware capabilities. Hence the SoC name, the
+version of the SAW hardware in that SoC and the distinction between cpu (big
+or Little) or cache, may be needed to uniquely identify the SAW register
+configuration and initialization data. The compatible string is used to
+indicate this parameter.
+
 PROPERTIES
 
 - compatible:
@@ -14,10 +23,13 @@  PROPERTIES
 	Value type: <string>
 	Definition: shall contain "qcom,saw2". A more specific value should be
 		    one of:
-			 "qcom,saw2-v1"
-			 "qcom,saw2-v1.1"
-			 "qcom,saw2-v2"
-			 "qcom,saw2-v2.1"
+			"qcom,saw2-v1"
+			"qcom,saw2-v1.1"
+			"qcom,saw2-v2"
+			"qcom,saw2-v2.1"
+			"qcom,apq8064-saw2-v1.1-cpu"
+			"qcom,msm8974-saw2-v2.1-cpu"
+			"qcom,apq8084-saw2-v2.1-cpu"
 
 - reg:
 	Usage: required
@@ -26,10 +38,17 @@  PROPERTIES
 		    the register region. An optional second element specifies
 		    the base address and size of the alias register region.
 
+- regulator:
+	Usage: optional
+	Value type: boolean
+	Definition: Indicates that this SPM device acts as a regulator device
+			device for the core (CPU or Cache) the SPM is attached
+			to.
 
 Example:
 
-	regulator@2099000 {
+	power-controller@2099000 {
 		compatible = "qcom,saw2";
 		reg = <0x02099000 0x1000>, <0x02009000 0x1000>;
+		regulator;
 	};
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 7bd2c94..628bcba 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -9,3 +9,10 @@  config QCOM_GSBI
           functions for connecting the underlying serial UART, SPI, and I2C
           devices to the output pins.
 
+config QCOM_PM
+	bool "Qualcomm Power Management"
+	depends on ARCH_QCOM
+	help
+	  QCOM Platform specific power driver to manage cores and L2 low power
+	  modes. It interface with various system drivers to put the cores in
+	  low power modes.
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index 4389012..931d385 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -1 +1,2 @@ 
 obj-$(CONFIG_QCOM_GSBI)	+=	qcom_gsbi.o
+obj-$(CONFIG_QCOM_PM)	+=	spm.o
diff --git a/drivers/soc/qcom/spm.c b/drivers/soc/qcom/spm.c
new file mode 100644
index 0000000..85b33ee
--- /dev/null
+++ b/drivers/soc/qcom/spm.c
@@ -0,0 +1,422 @@ 
+/*
+ * Copyright (c) 2011-2014, The Linux Foundation. All rights reserved.
+ * Copyright (c) 2014,2015, Linaro Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/err.h>
+#include <linux/platform_device.h>
+#include <linux/cpuidle.h>
+#include <linux/cpu_pm.h>
+#include <linux/qcom_scm.h>
+
+#include <asm/cpuidle.h>
+#include <asm/proc-fns.h>
+#include <asm/suspend.h>
+
+#define MAX_PMIC_DATA		2
+#define MAX_SEQ_DATA		64
+#define SPM_CTL_INDEX		0x7f
+#define SPM_CTL_INDEX_SHIFT	4
+#define SPM_CTL_EN		BIT(0)
+
+enum pm_sleep_mode {
+	PM_SLEEP_MODE_STBY,
+	PM_SLEEP_MODE_RET,
+	PM_SLEEP_MODE_SPC,
+	PM_SLEEP_MODE_PC,
+	PM_SLEEP_MODE_NR,
+};
+
+enum spm_reg {
+	SPM_REG_CFG,
+	SPM_REG_SPM_CTL,
+	SPM_REG_DLY,
+	SPM_REG_PMIC_DLY,
+	SPM_REG_PMIC_DATA_0,
+	SPM_REG_PMIC_DATA_1,
+	SPM_REG_VCTL,
+	SPM_REG_SEQ_ENTRY,
+	SPM_REG_SPM_STS,
+	SPM_REG_PMIC_STS,
+	SPM_REG_NR,
+};
+
+struct spm_reg_data {
+	const u8 *reg_offset;
+	u32 spm_cfg;
+	u32 spm_dly;
+	u32 pmic_dly;
+	u32 pmic_data[MAX_PMIC_DATA];
+	u8 seq[MAX_SEQ_DATA];
+	u8 start_index[PM_SLEEP_MODE_NR];
+};
+
+struct spm_driver_data {
+	void __iomem *reg_base;
+	const struct spm_reg_data *reg_data;
+};
+
+static const u8 spm_reg_offset_v2_1[SPM_REG_NR] = {
+	[SPM_REG_CFG]		= 0x08,
+	[SPM_REG_SPM_CTL]	= 0x30,
+	[SPM_REG_DLY]		= 0x34,
+	[SPM_REG_SEQ_ENTRY]	= 0x80,
+};
+
+/* SPM register data for 8974, 8084 */
+static const struct spm_reg_data spm_reg_8974_8084_cpu  = {
+	.reg_offset = spm_reg_offset_v2_1,
+	.spm_cfg = 0x1,
+	.spm_dly = 0x3C102800,
+	.seq = { 0x03, 0x0B, 0x0F, 0x00, 0x20, 0x80, 0x10, 0xE8, 0x5B, 0x03,
+		0x3B, 0xE8, 0x5B, 0x82, 0x10, 0x0B, 0x30, 0x06, 0x26, 0x30,
+		0x0F },
+	.start_index[PM_SLEEP_MODE_STBY] = 0,
+	.start_index[PM_SLEEP_MODE_SPC] = 3,
+};
+
+static const u8 spm_reg_offset_v1_1[SPM_REG_NR] = {
+	[SPM_REG_CFG]		= 0x08,
+	[SPM_REG_SPM_CTL]	= 0x20,
+	[SPM_REG_PMIC_DLY]	= 0x24,
+	[SPM_REG_PMIC_DATA_0]	= 0x28,
+	[SPM_REG_PMIC_DATA_1]	= 0x2C,
+	[SPM_REG_SEQ_ENTRY]	= 0x80,
+};
+
+/* SPM register data for 8064 */
+static const struct spm_reg_data spm_reg_8064_cpu = {
+	.reg_offset = spm_reg_offset_v1_1,
+	.spm_cfg = 0x1F,
+	.pmic_dly = 0x02020004,
+	.pmic_data[0] = 0x0084009C,
+	.pmic_data[1] = 0x00A4001C,
+	.seq = { 0x03, 0x0F, 0x00, 0x24, 0x54, 0x10, 0x09, 0x03, 0x01,
+		0x10, 0x54, 0x30, 0x0C, 0x24, 0x30, 0x0F },
+	.start_index[PM_SLEEP_MODE_STBY] = 0,
+	.start_index[PM_SLEEP_MODE_SPC] = 2,
+};
+
+static DEFINE_PER_CPU(struct spm_driver_data *, cpu_spm_drv);
+
+typedef int (*idle_fn)(int);
+static DEFINE_PER_CPU(idle_fn*, qcom_idle_ops);
+
+static inline void spm_register_write(struct spm_driver_data *drv,
+					enum spm_reg reg, u32 val)
+{
+	if (drv->reg_data->reg_offset[reg])
+		writel_relaxed(val, drv->reg_base +
+				drv->reg_data->reg_offset[reg]);
+}
+
+/* Ensure a guaranteed write, before return */
+static inline void spm_register_write_sync(struct spm_driver_data *drv,
+					enum spm_reg reg, u32 val)
+{
+	u32 ret;
+
+	if (!drv->reg_data->reg_offset[reg])
+		return;
+
+	do {
+		writel_relaxed(val, drv->reg_base +
+				drv->reg_data->reg_offset[reg]);
+		ret = readl_relaxed(drv->reg_base +
+				drv->reg_data->reg_offset[reg]);
+		if (ret == val)
+			break;
+		cpu_relax();
+	} while (1);
+}
+
+static inline u32 spm_register_read(struct spm_driver_data *drv,
+					enum spm_reg reg)
+{
+	return readl_relaxed(drv->reg_base + drv->reg_data->reg_offset[reg]);
+}
+
+static void spm_set_low_power_mode(enum pm_sleep_mode mode)
+{
+	struct spm_driver_data *drv = per_cpu(cpu_spm_drv,
+						smp_processor_id());
+	u32 start_index;
+	u32 ctl_val;
+
+	start_index = drv->reg_data->start_index[mode];
+
+	ctl_val = spm_register_read(drv, SPM_REG_SPM_CTL);
+	ctl_val &= ~(SPM_CTL_INDEX << SPM_CTL_INDEX_SHIFT);
+	ctl_val |= start_index << SPM_CTL_INDEX_SHIFT;
+	ctl_val |= SPM_CTL_EN;
+	spm_register_write_sync(drv, SPM_REG_SPM_CTL, ctl_val);
+}
+
+static int qcom_pm_collapse(unsigned long int unused)
+{
+	qcom_scm_cpu_power_down(QCOM_SCM_L2_ON);
+
+	/*
+	 * Returns here only if there was a pending interrupt and we did not
+	 * power down as a result.
+	 */
+	return -1;
+}
+
+static int qcom_cpu_standby(int cpuarg)
+{
+	spm_set_low_power_mode(PM_SLEEP_MODE_STBY);
+	cpu_do_idle();
+
+	return 0;
+}
+
+static int qcom_cpu_spc(int cpu)
+{
+	int ret;
+
+	spm_set_low_power_mode(PM_SLEEP_MODE_SPC);
+	cpu_pm_enter();
+	ret = cpu_suspend(0, qcom_pm_collapse);
+	/*
+	 * ARM common code may execute WFI, and if the SPM mode is not reset,
+	 * then we may accidently do power down state.
+	 * SPM is configured to reset to do STBY, but that relies on the
+	 * SPM state machine to be executed. When an interrupt is pending as we
+	 * enter idle state, SPM would not execute its state machine, so the
+	 * SPM may remain configured to do power down state.
+	 * Reset the state back to standby.
+	 */
+	spm_set_low_power_mode(PM_SLEEP_MODE_STBY);
+	cpu_pm_exit();
+
+	return ret;
+}
+
+static int qcom_idle_enter(int cpu, unsigned long index)
+{
+	if (!per_cpu(qcom_idle_ops, cpu)[index])
+		return -EOPNOTSUPP;
+
+	return per_cpu(qcom_idle_ops, cpu)[index](cpu);
+}
+
+const struct of_device_id qcom_idle_state_match[] __initconst = {
+	{ .compatible = "qcom,idle-state-stby", .data = qcom_cpu_standby },
+	{ .compatible = "qcom,idle-state-spc", .data = qcom_cpu_spc },
+	{ },
+};
+
+static int __init qcom_cpuidle_init(struct device_node *cpu_node, int cpu)
+{
+	const struct of_device_id *match_id;
+	struct device_node *state_node;
+	int i;
+	int state_count = 0;
+	idle_fn idle_fns[CPUIDLE_STATE_MAX];
+	idle_fn *fns;
+	cpumask_t mask;
+	bool use_scm_power_down = false;
+
+	for (i = 0; ; i++) {
+		state_node = of_parse_phandle(cpu_node, "cpu-idle-states", i);
+		if (!state_node)
+			break;
+
+		if (!of_device_is_available(state_node))
+			continue;
+
+		if (i == CPUIDLE_STATE_MAX) {
+			pr_warn("%s: cpuidle states reached max possible\n",
+					__func__);
+			break;
+		}
+
+		match_id = of_match_node(qcom_idle_state_match, state_node);
+		if (!match_id)
+			return -ENODEV;
+
+		idle_fns[state_count] = match_id->data;
+
+		/* Check if any of the states allow power down */
+		if (match_id->data == qcom_cpu_spc)
+			use_scm_power_down = true;
+
+		state_count++;
+	}
+
+	if (!state_count) {
+		pr_warn("No idle ops founds for cpu %d\n", cpu);
+		return -ENODEV;
+	}
+
+	fns = kcalloc(state_count, sizeof(*fns), GFP_KERNEL);
+	if (!fns)
+		return -ENOMEM;
+
+	for (i = 0; i < state_count; i++)
+		fns[i] = idle_fns[i];
+
+	if (use_scm_power_down) {
+		/* We have atlease one power down mode */
+		cpumask_clear(&mask);
+		cpumask_set_cpu(cpu, &mask);
+		qcom_scm_set_warm_boot_addr(cpu_resume, &mask);
+	}
+
+	per_cpu(qcom_idle_ops, cpu) = fns;
+
+	/*
+	 * Condition: cpuidle_driver_register() needs to happen before
+	 * cpuidle_register_device().
+	 * Check if the SPM probe has happened -
+	 * - If SPM probed successfully before arm_idle_init(), then defer
+	 *   the registration of cpuidle_device back to arm_idle_init()
+	 * - If the SPM probe happens in the future, then let the SPM probe
+	 *   register the cpuidle device, return -ENOSYS.
+	 */
+	return per_cpu(cpu_spm_drv, cpu) ? 0 : -ENOSYS;
+}
+
+struct cpuidle_ops qcom_kpss_v1_cpuidle_ops __initdata = {
+	.name = "qcom,kpss-acc-v1",
+	.suspend = qcom_idle_enter,
+	.init = qcom_cpuidle_init,
+};
+
+struct cpuidle_ops qcom_kpss_v2_cpuidle_ops __initdata = {
+	.name = "qcom,kpss-acc-v2",
+	.suspend = qcom_idle_enter,
+	.init = qcom_cpuidle_init,
+};
+
+static struct spm_driver_data *spm_get_drv(struct platform_device *pdev,
+		int *spm_cpu)
+{
+	struct spm_driver_data *drv = NULL;
+	struct device_node *cpu_node, *saw_node;
+	int cpu;
+	bool found;
+
+	for_each_possible_cpu(cpu) {
+		cpu_node = of_cpu_device_node_get(cpu);
+		if (!cpu_node)
+			continue;
+		saw_node = of_parse_phandle(cpu_node, "qcom,saw", 0);
+		found = (saw_node == pdev->dev.of_node);
+		of_node_put(saw_node);
+		of_node_put(cpu_node);
+		if (found)
+			break;
+	}
+
+	if (found) {
+		drv = devm_kzalloc(&pdev->dev, sizeof(*drv), GFP_KERNEL);
+		if (drv)
+			*spm_cpu = cpu;
+	}
+
+	return drv;
+}
+
+static const struct of_device_id spm_match_table[] = {
+	{ .compatible = "qcom,msm8974-saw2-v2.1-cpu",
+	  .data = &spm_reg_8974_8084_cpu },
+	{ .compatible = "qcom,apq8084-saw2-v2.1-cpu",
+	  .data = &spm_reg_8974_8084_cpu },
+	{ .compatible = "qcom,apq8064-saw2-v1.1-cpu",
+	  .data = &spm_reg_8064_cpu },
+	{ },
+};
+
+static int spm_dev_probe(struct platform_device *pdev)
+{
+	struct spm_driver_data *drv;
+	struct resource *res;
+	const struct of_device_id *match_id;
+	void __iomem *addr;
+	int cpu;
+	int ret = 0;
+
+	drv = spm_get_drv(pdev, &cpu);
+	if (!drv)
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	drv->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(drv->reg_base))
+		return PTR_ERR(drv->reg_base);
+
+	match_id = of_match_node(spm_match_table, pdev->dev.of_node);
+	if (!match_id)
+		return -ENODEV;
+
+	drv->reg_data = match_id->data;
+
+	/* Write the SPM sequences first.. */
+	addr = drv->reg_base + drv->reg_data->reg_offset[SPM_REG_SEQ_ENTRY];
+	__iowrite32_copy(addr, drv->reg_data->seq,
+			ARRAY_SIZE(drv->reg_data->seq) / 4);
+
+	/*
+	 * ..and then the control registers.
+	 * On some SoC if the control registers are written first and if the
+	 * CPU was held in reset, the reset signal could trigger the SPM state
+	 * machine, before the sequences are completely written.
+	 */
+	spm_register_write(drv, SPM_REG_CFG, drv->reg_data->spm_cfg);
+	spm_register_write(drv, SPM_REG_DLY, drv->reg_data->spm_dly);
+	spm_register_write(drv, SPM_REG_PMIC_DLY, drv->reg_data->pmic_dly);
+	spm_register_write(drv, SPM_REG_PMIC_DATA_0,
+				drv->reg_data->pmic_data[0]);
+	spm_register_write(drv, SPM_REG_PMIC_DATA_1,
+				drv->reg_data->pmic_data[1]);
+
+	per_cpu(cpu_spm_drv, cpu) = drv;
+
+	/* If the cpuidle ops have already been registered with cpuidle,
+	 * then we have been waiting on this SPM probe to register the
+	 * cpuidle device.
+	 */
+	if (per_cpu(qcom_idle_ops, cpu)) {
+		struct cpuidle_device *dev;
+
+		dev = devm_kzalloc(&pdev->dev, sizeof(*dev), GFP_KERNEL);
+		if (!dev)
+			return -ENOMEM;
+		dev->cpu = cpu;
+		ret = cpuidle_register_device(dev);
+	}
+
+	return ret;
+}
+
+static struct platform_driver spm_driver = {
+	.probe = spm_dev_probe,
+	.driver = {
+		.name = "saw",
+		.of_match_table = spm_match_table,
+	},
+};
+module_platform_driver(spm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("SAW power controller driver");
+MODULE_ALIAS("platform:saw");