Subject: [PATCH v13 03/10] qcom: spm: Add Subsystem Power Manager driver

From: [email-masked] (Daniel Lezcano)
Date: Thu, 27 Nov 2014 09:52:35 +0100

On 11/27/2014 06:24 AM, Lina Iyer 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 <[email-masked]>,
> Ai Li <[email-masked]>, Praveen Chidambaram <[email-masked]>
> Original tree available at -
> git://codeaurora.org/quic/la/kernel/msm-3.10.git
>
> Signed-off-by: Lina Iyer <[email-masked]>
> Reviewed-by: Kevin Hilman <[email-masked]>

[ ... ]

> +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 = false;
> +
> +	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);
> +		if (saw_node) {
> +			if (saw_node == pdev->dev.of_node)
> +				found = true;
> +			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 const struct qcom_cpu_pm_ops lpm_ops = {
> +	.standby = qcom_cpu_standby,
> +	.spc = qcom_cpu_spc,
> +};
> +
> +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 = -EINVAL;
> +	static bool cpuidle_drv_init;

         ^^^^^^^^^

As already said in a previous comment, please find a way to remove that.

> +	const struct platform_device_info qcom_cpuidle_info = {
> +		.name	= "qcom_cpuidle",
> +		.id	= -1,
> +		.data = &lpm_ops,
> +		.size_data = sizeof(lpm_ops),
> +	};
> +
> +	drv = spm_get_drv(pdev, &cpu);
> +	if (!drv || cpu < 0)
> +		return -EINVAL;

As already said in a previous comment, it is not possible to have "cpu < 
0" with "drv != NULL", so except I am missing something the test should be:

	if (!drv)
		return -EINVAL;

There is something wrong with the init sequence. Don't you find weird 
you have to backward search for the cpu belonging to the pdev each time 
the probe function is called ?

> +
> +	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'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();
> +	per_cpu(cpu_spm_drv, cpu) = drv;
> +
> +	if (!cpuidle_drv_init) {
> +		platform_device_register_full(&qcom_cpuidle_info);
> +		cpuidle_drv_init = true;
> +	}
> +
> +	return 0;
> +}
> +
> +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");
> diff --git a/include/soc/qcom/pm.h b/include/soc/qcom/pm.h
> new file mode 100644
> index 0000000..d9a56d7
> --- /dev/null
> +++ b/include/soc/qcom/pm.h
> @@ -0,0 +1,31 @@
> +/*
> + * Copyright (c) 2009-2014, The Linux Foundation. All rights reserved.
> + *
> + * This software is licensed under the terms of the GNU General Public
> + * License version 2, as published by the Free Software Foundation, and
> + * may be copied, distributed, and modified under those terms.
> + *
> + * 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.
> + *
> + */
> +
> +#ifndef __QCOM_PM_H
> +#define __QCOM_PM_H
> +
> +enum pm_sleep_mode {
> +	PM_SLEEP_MODE_STBY,
> +	PM_SLEEP_MODE_RET,
> +	PM_SLEEP_MODE_SPC,
> +	PM_SLEEP_MODE_PC,
> +	PM_SLEEP_MODE_NR,
> +};
> +
> +struct qcom_cpu_pm_ops {
> +	int (*standby)(void *data);
> +	int (*spc)(void *data);
> +};
> +
> +#endif  /* __QCOM_PM_H */
>

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