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Subject: Re: [PATCH 2/5] thermal: qcom: Add support for LMh driver
To:     Bjorn Andersson <bjorn.andersson@linaro.org>
Cc:     agross@kernel.org, rui.zhang@intel.com, daniel.lezcano@linaro.org,
        viresh.kumar@linaro.org, rjw@rjwysocki.net, robh+dt@kernel.org,
        linux-arm-msm@vger.kernel.org, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org, devicetree@vger.kernel.org
References: <20210608222926.2707768-1-thara.gopinath@linaro.org>
 <20210608222926.2707768-3-thara.gopinath@linaro.org>
 <YMfBtSap7fR3rdku@builder.lan>
From:   Thara Gopinath <thara.gopinath@linaro.org>
Message-ID: <4996de55-daa9-18a4-3c03-cf194d85500e@linaro.org>
Date:   Mon, 14 Jun 2021 21:38:09 -0400
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Hi Bjorn,

Thanks for the review


On 6/14/21 4:53 PM, Bjorn Andersson wrote:
> On Tue 08 Jun 17:29 CDT 2021, Thara Gopinath wrote:
> 
>> Driver enabling various pieces of Limits Management Hardware(LMh) for cpu
>> cluster0 and cpu cluster1 namely kick starting monitoring of temperature,
>> current, battery current violations, enabling reliability algorithm and
>> setting up various temperature limits.
>>
>> The following has been explained in the cover letter. I am including this
>> here so that this remains in the commit message as well.
>>
>> LMh is a hardware infrastructure on some Qualcomm SoCs that can enforce
>> temperature and current limits as programmed by software for certain IPs
>> like CPU. On many newer SoCs LMh is configured by firmware/TZ and no
>> programming is needed from the kernel side. But on certain SoCs like sdm845
>> the firmware does not do a complete programming of the h/w. On such SoCs
>> kernel software has to explicitly set up the temperature limits and turn on
>> various monitoring and enforcing algorithms on the hardware.
>>
>> Signed-off-by: Thara Gopinath <thara.gopinath@linaro.org>
>> ---
>>   drivers/thermal/qcom/Kconfig  |  10 ++
>>   drivers/thermal/qcom/Makefile |   1 +
>>   drivers/thermal/qcom/lmh.c    | 244 ++++++++++++++++++++++++++++++++++
>>   3 files changed, 255 insertions(+)
>>   create mode 100644 drivers/thermal/qcom/lmh.c
>>
>> diff --git a/drivers/thermal/qcom/Kconfig b/drivers/thermal/qcom/Kconfig
>> index 8d5ac2df26dc..c95b95e254d7 100644
>> --- a/drivers/thermal/qcom/Kconfig
>> +++ b/drivers/thermal/qcom/Kconfig
>> @@ -31,3 +31,13 @@ config QCOM_SPMI_TEMP_ALARM
>>   	  trip points. The temperature reported by the thermal sensor reflects the
>>   	  real time die temperature if an ADC is present or an estimate of the
>>   	  temperature based upon the over temperature stage value.
>> +
>> +config QCOM_LMH
>> +	tristate "Qualcomm Limits Management Hardware"
>> +	depends on ARCH_QCOM
>> +	help
>> +	  This enables initialization of Qualcomm limits management
>> +	  hardware(LMh). LMh allows for h/w enforced mitigation for cpus based on
>> +	  input from temperature and current sensors.  On many newer Qualcomm SoCs
>> +	  LMH is configure in the firmware and this feature need not be enabled.
>> +	  However, on certain SoCs like sdm845 LMH has to be configured from HLOS.
>> diff --git a/drivers/thermal/qcom/Makefile b/drivers/thermal/qcom/Makefile
>> index 252ea7d9da0b..0fa2512042e7 100644
>> --- a/drivers/thermal/qcom/Makefile
>> +++ b/drivers/thermal/qcom/Makefile
>> @@ -5,3 +5,4 @@ qcom_tsens-y			+= tsens.o tsens-v2.o tsens-v1.o tsens-v0_1.o \
>>   				   tsens-8960.o
>>   obj-$(CONFIG_QCOM_SPMI_ADC_TM5)	+= qcom-spmi-adc-tm5.o
>>   obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
>> +obj-$(CONFIG_QCOM_LMH)		+= lmh.o
>> diff --git a/drivers/thermal/qcom/lmh.c b/drivers/thermal/qcom/lmh.c
>> new file mode 100644
>> index 000000000000..8741a36cb674
>> --- /dev/null
>> +++ b/drivers/thermal/qcom/lmh.c
>> @@ -0,0 +1,244 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +
>> +/*
>> + * Copyright (C) 2021, Linaro Limited. All rights reserved.
>> + */
>> +#include <linux/module.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/irqdomain.h>
>> +#include <linux/err.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/slab.h>
>> +#include <linux/qcom_scm.h>
>> +
>> +#define LMH_NODE_DCVS			0x44435653
>> +#define LMH_CLUSTER0_NODE_ID		0x6370302D
>> +#define LMH_CLUSTER1_NODE_ID		0x6370312D
>> +
>> +#define LMH_SUB_FN_THERMAL		0x54484D4C
>> +#define LMH_SUB_FN_CRNT			0x43524E54
>> +#define LMH_SUB_FN_REL			0x52454C00
>> +#define LMH_SUB_FN_BCL			0x42434C00
>> +
>> +#define LMH_ALGO_MODE_ENABLE		0x454E424C
>> +#define LMH_TH_HI_THRESHOLD		0x48494748
>> +#define LMH_TH_LOW_THRESHOLD		0x4C4F5700
>> +#define LMH_TH_ARM_THRESHOLD		0x41524D00
>> +
>> +#define LMH_TH_HI_TEMP			95000
>> +#define LMH_TH_LOW_TEMP			94500
>> +#define LMH_TH_ARM_TEMP			65000
>> +
>> +#define LMH_REG_DCVS_INTR_CLR		0x8
>> +
>> +struct lmh_hw_data {
>> +	void __iomem *base;
>> +	struct irq_domain *domain;
>> +	int irq;
>> +	u32 payload[5];
>> +	u32 payload_size;
>> +	u32 cpu_id;
>> +};
>> +
>> +static void update_payload(struct lmh_hw_data *lmh_data, u32 fn, u32 reg, u32 val)
> 
> Please pass fn, reg and val in the scm function call instead and stuff
> the payload array in the scm driver instead.

Sure . I will redo this part.

> 
>> +{
>> +	lmh_data->payload[0] = fn;
>> +	lmh_data->payload[1] = 0;
>> +	lmh_data->payload[2] = reg;
>> +	lmh_data->payload[3] = 1;
>> +	lmh_data->payload[4] = val;
>> +}
>> +
>> +static irqreturn_t lmh_handle_irq(int hw_irq, void *data)
>> +{
>> +	struct lmh_hw_data *lmh_data = data;
>> +	int irq = irq_find_mapping(lmh_data->domain, 0);
>> +
>> +	/*
>> +	 * Disable interrupt and call the cpufreq driver to handle the interrupt
>> +	 * cpufreq will enable the interrupt once finished processing.
>> +	 */
>> +	disable_irq_nosync(lmh_data->irq);
> 
> The contract between this driver's disabling of the IRQ and the
> cpufreq-hw driver's enabling it when we're done polling does worry me.
> 
> In the case of EPSS, don't we disable the interrupt during the polling
> there as well? If that's the case wouldn't it be better to implement
> irq_chip->irq_disable and have the cpufreq-hw driver do the disable in
> both cases?

Yes. You are right. In case of EPSS, the cpufreq-hw will have to disable 
the interrupt. I did think of the approach you suggested here. My only 
issue is that we will dispatch the interrupt to cpufreq-hw without it 
disabling it and hence the interrupt could fire again, right ?


> 
>> +	if (irq)
>> +		generic_handle_irq(irq);
>> +
>> +	return 0;
>> +}
>> +
>> +static void lmh_enable_interrupt(struct irq_data *d)
>> +{
>> +	struct lmh_hw_data *lmh_data = irq_data_get_irq_chip_data(d);
>> +
>> +	/* Clear the existing interrupt */
>> +	writel_relaxed(0xFF, lmh_data->base + LMH_REG_DCVS_INTR_CLR);
> 
> Please avoid using _relaxed versions of writel, unless there's a strong
> reason and please lowercase the hex digits.

Sure.

> 
>> +	enable_irq(lmh_data->irq);
>> +}
>> +
>> +static struct irq_chip lmh_irq_chip = {
>> +	.name           = "lmh",
>> +	.irq_enable	= lmh_enable_interrupt,
>> +};
>> +
>> +static int lmh_irq_map(struct irq_domain *d, unsigned int irq, irq_hw_number_t hw)
>> +{
>> +	struct lmh_hw_data *lmh_data = d->host_data;
>> +
>> +	irq_set_chip_and_handler(irq, &lmh_irq_chip, handle_simple_irq);
>> +	irq_set_chip_data(irq, lmh_data);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct irq_domain_ops lmh_irq_ops = {
>> +	.map = lmh_irq_map,
>> +	.xlate = irq_domain_xlate_onecell,
>> +};
>> +
>> +static int lmh_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev;
>> +	struct device_node *np;
>> +	struct lmh_hw_data *lmh_data;
>> +	u32 node_id;
>> +	int ret;
>> +
>> +	dev = &pdev->dev;
>> +	np = dev->of_node;
>> +	if (!np)
>> +		return -EINVAL;
>> +
>> +	lmh_data = devm_kzalloc(dev, sizeof(*lmh_data), GFP_KERNEL);
>> +	if (!lmh_data)
>> +		return -ENOMEM;
>> +
>> +	lmh_data->base = devm_platform_ioremap_resource(pdev, 0);
>> +	if (IS_ERR(lmh_data->base))
>> +		return PTR_ERR(lmh_data->base);
>> +
>> +	ret = of_property_read_u32(np, "qcom,lmh-cpu-id", &lmh_data->cpu_id);
>> +	if (ret)
>> +		return -ENODEV;
>> +
>> +	/*
>> +	 * Only sdm845 has lmh hardware currently enabled from hlos. If this is needed
>> +	 * for other platforms, revisit this to check if the <cpu-id, node-id> should be part
>> +	 * of a dt match table.
>> +	 */
>> +	if (lmh_data->cpu_id == 0) {
>> +		node_id = LMH_CLUSTER0_NODE_ID;
>> +	} else if (lmh_data->cpu_id == 4) {
>> +		node_id = LMH_CLUSTER1_NODE_ID;
>> +	} else {
>> +		dev_err(dev, "Wrong cpu id associated with lmh node\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	/* Payload size is five bytes for now */
>> +	lmh_data->payload_size = 5 * sizeof(u32);
>> +
>> +	platform_set_drvdata(pdev, lmh_data);
>> +
>> +	if (!qcom_scm_lmh_dcvsh_available())
>> +		return -EINVAL;
>> +
>> +	/* Enable Thermal Algorithm */
>> +	update_payload(lmh_data, LMH_SUB_FN_THERMAL, LMH_ALGO_MODE_ENABLE, 1);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d enabling thermal subfunction\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Enable Current Sensing Algorithm */
>> +	update_payload(lmh_data, LMH_SUB_FN_CRNT, LMH_ALGO_MODE_ENABLE, 1);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d enabling current subfunction\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Enable Reliability Algorithm */
>> +	update_payload(lmh_data, LMH_SUB_FN_REL, LMH_ALGO_MODE_ENABLE, 1);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d enabling reliability subfunction\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Enable BCL Algorithm */
>> +	update_payload(lmh_data, LMH_SUB_FN_BCL, LMH_ALGO_MODE_ENABLE, 1);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d enabling BCL subfunction\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	ret = qcom_scm_lmh_profile_change(0x1);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d changing profile\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	/* Set default thermal trips */
>> +	update_payload(lmh_data, LMH_SUB_FN_THERMAL, LMH_TH_ARM_THRESHOLD, LMH_TH_ARM_TEMP);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error setting thermal ARM thershold%d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	update_payload(lmh_data, LMH_SUB_FN_THERMAL, LMH_TH_HI_THRESHOLD, LMH_TH_HI_TEMP);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error setting thermal HI thershold%d\n", ret);
>> +		return ret;
>> +	}
>> +	update_payload(lmh_data, LMH_SUB_FN_THERMAL, LMH_TH_LOW_THRESHOLD, LMH_TH_LOW_TEMP);
>> +	ret = qcom_scm_lmh_dcvsh(lmh_data->payload, lmh_data->payload_size,
>> +				 LMH_NODE_DCVS, node_id, 0);
>> +	if (ret) {
>> +		dev_err(dev, "Error setting thermal ARM thershold%d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	lmh_data->irq = platform_get_irq(pdev, 0);
>> +	lmh_data->domain = irq_domain_add_linear(np, 1, &lmh_irq_ops, lmh_data);
>> +	if (!lmh_data->domain) {
>> +		dev_err(dev, "Error adding irq_domain\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	ret = devm_request_irq(dev, lmh_data->irq, lmh_handle_irq,
>> +			       IRQF_TRIGGER_HIGH | IRQF_ONESHOT | IRQF_NO_SUSPEND,
>> +			       "lmh-irq", lmh_data);
>> +	if (ret) {
>> +		dev_err(dev, "Error %d registering irq %x\n", ret, lmh_data->irq);
>> +		irq_domain_remove(lmh_data->domain);
>> +		return ret;
>> +	}
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id lmh_table[] = {
>> +	{ .compatible = "qcom,msm-hw-limits", },
> 
> Don't we need platform specific compatibles? Perhaps
> "qcom,<platform>-lmh"?

Yes considering that is the norm, I will follow it.

> 
> If we're going with a generic compatible I think that should be done in
> addition to a platform-specific one (and qcom,lmh should be sufficien >
>> +	{},
> 
> Please omit the comma here.

Ok.

> 
>> +};
> 
> Driver is tristate, so you need a MODULE_DEVICE_TABLE(of, lmh_table);
> here, to make sure the module is loaded automatically based on the
> compatible strings in DT.

Right. I will fix it .
> 
> Regards,
> Bjorn
> 
>> +
>> +static struct platform_driver lmh_driver = {
>> +	.probe = lmh_probe,
>> +	.driver = {
>> +		.name = "qcom-lmh",
>> +		.of_match_table = lmh_table,
>> +	},
>> +};
>> +module_platform_driver(lmh_driver);
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_DESCRIPTION("QCOM LMH driver");
>> -- 
>> 2.25.1
>>

-- 
Warm Regards
Thara (She/Her/Hers)