Subject: [PATCH v9 2/9] qcom: spm: Add Subsystem Power Manager driver

From: [email-masked] (Stephen Boyd)
Date: Fri, 14 Nov 2014 14:46:20 -0800

On 10/24, Lina Iyer wrote:
> diff --git a/drivers/soc/qcom/spm.c b/drivers/soc/qcom/spm.c
> new file mode 100644
> index 0000000..ee2e3ca
> --- /dev/null
> +++ b/drivers/soc/qcom/spm.c
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/delay.h>

Is this used?

> +#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 <asm/proc-fns.h>
> +#include <asm/suspend.h>
> +
> +#include <soc/qcom/pm.h>
> +#include <soc/qcom/pm.h>
> +#include <soc/qcom/scm.h>
> +#include <soc/qcom/scm-boot.h>
> +
> +
> +#define SCM_CMD_TERMINATE_PC	(0x2)
> +#define SCM_FLUSH_FLAG_MASK	(0x3)
> +#define SCM_L2_ON		(0x0)
> +#define SCM_L2_OFF		(0x1)
> +#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)

Nitpick, why aren't these also tabbed out?

> +
> +/**
> + * spm_set_low_power_mode() - Configure SPM start address for low power mode
> + * @mode: SPM LPM mode to enter
> + */
> +int qcom_spm_set_low_power_mode(enum pm_sleep_mode mode)

static?

> +{
> +	struct spm_driver_data *drv = this_cpu_ptr(&cpu_spm_drv);
> +	u32 start_index;
> +	u32 ctl_val;
> +
> +	if (!drv->available)
> +		return -ENXIO;

It would be nice if we didn't need this by only registering the
cpuidle device for this CPU once we've initialized the SPM
hardware.

> +
> +	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(drv, SPM_REG_SPM_CTL, ctl_val);
> +
> +	/* Ensure we have written the start address */
> +	wmb();
> +
> +	return 0;
> +}
> +
> +static int qcom_pm_collapse(unsigned long int unused)
> +{
> +	int ret;
> +	u32 flag;
> +	int cpu = smp_processor_id();
> +
> +	ret = scm_set_warm_boot_addr(cpu_resume, cpu);
> +	if (ret) {
> +		pr_err("Failed to set warm boot address for cpu %d\n", cpu);

Do we want this print? Won't it start spamming the log if we go
idle and we can't set the flag? Maybe we should just be silent
and return an error.

> +		return ret;
> +	}
> +
> +	flag = SCM_L2_ON & SCM_FLUSH_FLAG_MASK;
> +	scm_call_atomic1(SCM_SVC_BOOT, SCM_CMD_TERMINATE_PC, flag);
> +
> +	/**
> +	 *  Returns here only if there was a pending interrupt and we did not
> +	 *  power down as a result.
> +	 */
> +	return 0;
> +}
[...]
> +
> +static struct qcom_cpu_pm_ops lpm_ops = {

const?

> +	.standby = qcom_cpu_standby,
> +	.spc = qcom_cpu_spc,
> +};
> +
> +struct platform_device qcom_cpuidle_device = {
> +	.name              = "qcom_cpuidle",
> +	.id                = -1,
> +	.dev.platform_data = &lpm_ops,
> +};

This can be created dynamically instead of living statically.

> +
> +static int spm_dev_probe(struct platform_device *pdev)
> +{
[...]
> +
> +	match_id = of_match_node(spm_match_table, pdev->dev.of_node);
> +	if (!match_id)
> +		return -ENODEV;
> +
> +	drv->reg_data = match_id->data;
> +	if (!drv->reg_data)
> +		return -EINVAL;

This check seems useless. We control the .data field right above
this function so there better be some reg_data.

> +
> +	/* Write the SPM sequences, first.. */
> +	addr = drv->reg_base + drv->reg_data->reg_offset[SPM_REG_SEQ_ENTRY];
> +	seq_data = (const u32 *)drv->reg_data->seq;

Why do we need a cast?

> +	__iowrite32_copy(addr, seq_data, ARRAY_SIZE(drv->reg_data->seq)/4);

nitpick: space around that / please.

> +
> +	/* ..and then, the control registers.
> +	 * On some SoC's 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]);
> +
> +	/**
> +	 * Ensure all observers see the above register writes before the
> +	 * cpuidle driver is allowed to use the SPM.
> +	 */
> +	wmb();
> +	drv->available = true;
> +
> +	if ((cpu > -1) && !cpuidle_drv_init) {

Nitpick: () are unnecessary.

> +		platform_device_register(&qcom_cpuidle_device);
> +		cpuidle_drv_init = true;
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver spm_driver = {
> +	.probe = spm_dev_probe,
> +	.driver = {
> +		.name = "qcom,spm",

This is an odd driver name with the "qcom," part. Maybe call it "spm" or "saw"?

> +		.of_match_table = spm_match_table,
> +	},
> +};
> +
> +module_platform_driver(spm_driver);

MODULE_LICENSE()?
MODULE_ALIAS()?

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