Message-ID: <7h61a94zy0.fsf@deeprootsystems.com>
Date:	Mon, 09 Mar 2015 14:35:03 -0700
From:	Kevin Hilman <khilman@...nel.org>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-mediatek@...ts.infradead.org, kernel@...gutronix.de
Subject: Re: [PATCH 2/4] soc: Mediatek: Add SCPSYS power domain driver

Sascha Hauer <s.hauer@...gutronix.de> writes:

> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>

A bit of a changelog here would be useful describing this driver, that
it's only covering part of the device (e.g. power controller) with more
to come, dependency on the syscon driver, etc.

> ---
>  drivers/soc/mediatek/Kconfig             |   6 +
>  drivers/soc/mediatek/Makefile            |   1 +
>  drivers/soc/mediatek/mtk-scpsys.c        | 398 +++++++++++++++++++++++++++++++
>  include/dt-bindings/power/mt8173-power.h |  15 ++
>  4 files changed, 420 insertions(+)
>  create mode 100644 drivers/soc/mediatek/mtk-scpsys.c
>  create mode 100644 include/dt-bindings/power/mt8173-power.h
>
> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> index b91665a..4736f5b 100644
> --- a/drivers/soc/mediatek/Kconfig
> +++ b/drivers/soc/mediatek/Kconfig
> @@ -9,3 +9,9 @@ config MTK_PMIC_WRAP
>  	  Say yes here to add support for MediaTek PMIC Wrapper found
>  	  on the MT8135 and MT8173 SoCs. The PMIC wrapper is a proprietary
>  	  hardware to connect the PMIC.
> +
> +config MTK_SCPSYS
> +	tristate "MediaTek SCPSYS Support"
> +	help
> +	  Say yes here to add support for the MediaTek SCPSYS power domain
> +	  driver.
> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> index ecaf4de..ce88693 100644
> --- a/drivers/soc/mediatek/Makefile
> +++ b/drivers/soc/mediatek/Makefile
> @@ -1 +1,2 @@
>  obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o
> +obj-$(CONFIG_MTK_SCPSYS) += mtk-scpsys.o
> diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> new file mode 100644
> index 0000000..8bbd2e8
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-scpsys.c
> @@ -0,0 +1,398 @@
> +/*
> + * Copyright (c) 2015 Pengutronix, Sascha Hauer <kernel@...gutronix.de>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License 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/clk.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/pm_domain.h>
> +#include <linux/delay.h>
> +#include <dt-bindings/power/mt8173-power.h>
> +#include <linux/mfd/syscon.h>
> +
> +#define SPM_VDE_PWR_CON			0x0210
> +#define SPM_MFG_PWR_CON			0x0214
> +#define SPM_VEN_PWR_CON			0x0230
> +#define SPM_ISP_PWR_CON			0x0238
> +#define SPM_DIS_PWR_CON			0x023c
> +#define SPM_VEN2_PWR_CON		0x0298
> +#define SPM_AUDIO_PWR_CON		0x029c
> +#define SPM_MFG_2D_PWR_CON		0x02c0
> +#define SPM_MFG_ASYNC_PWR_CON		0x02c4
> +#define SPM_USB_PWR_CON			0x02cc
> +#define SPM_PWR_STATUS			0x060c
> +#define SPM_PWR_STATUS_2ND		0x0610
> +
> +#define PWR_RST_B_BIT			BIT(0)
> +#define PWR_ISO_BIT			BIT(1)
> +#define PWR_ON_BIT			BIT(2)
> +#define PWR_ON_2ND_BIT			BIT(3)
> +#define PWR_CLK_DIS_BIT			BIT(4)
> +
> +#define DIS_PWR_STA_MASK		BIT(3)
> +#define MFG_PWR_STA_MASK		BIT(4)
> +#define ISP_PWR_STA_MASK		BIT(5)
> +#define VDE_PWR_STA_MASK		BIT(7)
> +#define VEN2_PWR_STA_MASK		BIT(20)
> +#define VEN_PWR_STA_MASK		BIT(21)
> +#define MFG_2D_PWR_STA_MASK		BIT(22)
> +#define MFG_ASYNC_PWR_STA_MASK		BIT(23)
> +#define AUDIO_PWR_STA_MASK		BIT(24)
> +#define USB_PWR_STA_MASK		BIT(25)
> +
> +/*
> + * The Infracfg unit has bus protection bits. We enable the bus protection
> + * for disabled power domains so that the system does not hang when some unit
> + * accesses the bus while in power down.
> + */

Hmm, why don't you want to know if some device is accessing another
device which is in a domain that is powered down?   Seems like this is a
good way to hide real bugs.

> +#define INFRA_TOPAXI_PROTECTEN		0x0220
> +#define INFRA_TOPAXI_PROTECTSTA1	0x0228
> +
> +#define TOP_AXI_PROT_EN_MFG_SNOOP_OUT	BIT(23)
> +#define TOP_AXI_PROT_EN_MFG_M1		BIT(22)
> +#define TOP_AXI_PROT_EN_MFG_M0		BIT(21)
> +#define TOP_AXI_PROT_EN_IOMMU		BIT(20)
> +#define TOP_AXI_PROT_EN_GCPU		BIT(19)
> +#define TOP_AXI_PROT_EN_CQ_DMA		BIT(18)
> +#define TOP_AXI_PROT_EN_DEBUGSYS	BIT(17)
> +#define TOP_AXI_PROT_EN_PERI_M1		BIT(16)
> +#define TOP_AXI_PROT_EN_PERI_M0		BIT(15)
> +#define TOP_AXI_PROT_EN_MFG_S		BIT(14)
> +#define TOP_AXI_PROT_EN_CCI_M2		BIT(13)
> +#define TOP_AXI_PROT_EN_L2SS_ADD	BIT(12)
> +#define TOP_AXI_PROT_EN_L2SS_SMI	BIT(11)
> +#define TOP_AXI_PROT_EN_L2C_M2		BIT(9)
> +#define TOP_AXI_PROT_EN_MMAPB_S		BIT(6)
> +#define TOP_AXI_PROT_EN_MM_M1		BIT(2)
> +#define TOP_AXI_PROT_EN_MM_M0		BIT(1)
> +#define TOP_AXI_PROT_EN_MCI_M2		BIT(0)
> +
> +struct scp_domain_data {
> +	const char *name;
> +	u32 sta_mask;
> +	int ctl_offs;
> +	u32 sram_pdn_bits;
> +	u32 sram_pdn_ack_bits;
> +	u32 bus_prot_mask;
> +	int id;
> +};
> +
> +static struct scp_domain_data scp_domain_data[] = {
> +	{
> +		.id = MT8173_POWER_DOMAIN_VDE,
> +		.name = "vde",
> +		.sta_mask = VDE_PWR_STA_MASK,
> +		.ctl_offs = SPM_VDE_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(12, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_MFG,
> +		.name = "mfg",
> +		.sta_mask = MFG_PWR_STA_MASK,
> +		.ctl_offs = SPM_MFG_PWR_CON,
> +		.sram_pdn_bits = GENMASK(13, 8),
> +		.sram_pdn_ack_bits = GENMASK(21, 16),
> +		.bus_prot_mask = TOP_AXI_PROT_EN_MFG_S | TOP_AXI_PROT_EN_MFG_M0 |
> +			TOP_AXI_PROT_EN_MFG_M1 | TOP_AXI_PROT_EN_MFG_SNOOP_OUT,
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_VEN,
> +		.name = "ven",
> +		.sta_mask = VEN_PWR_STA_MASK,
> +		.ctl_offs = SPM_VEN_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(15, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_ISP,
> +		.name = "isp",
> +		.sta_mask = ISP_PWR_STA_MASK,
> +		.ctl_offs = SPM_ISP_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(13, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_DIS,
> +		.name = "dis",
> +		.sta_mask = DIS_PWR_STA_MASK,
> +		.ctl_offs = SPM_DIS_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(12, 12),
> +		.bus_prot_mask = TOP_AXI_PROT_EN_MM_M0 | TOP_AXI_PROT_EN_MM_M1,
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_VEN2,
> +		.name = "ven2",
> +		.sta_mask = VEN2_PWR_STA_MASK,
> +		.ctl_offs = SPM_VEN2_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(15, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_AUDIO,
> +		.name = "audio",
> +		.sta_mask = AUDIO_PWR_STA_MASK,
> +		.ctl_offs = SPM_AUDIO_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(15, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_MFG_2D,
> +		.name = "mfg_2d",
> +		.sta_mask = MFG_2D_PWR_STA_MASK,
> +		.ctl_offs = SPM_MFG_2D_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(13, 12),
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_MFG_ASYNC,
> +		.name = "mfg_async",
> +		.sta_mask = MFG_ASYNC_PWR_STA_MASK,
> +		.ctl_offs = SPM_MFG_ASYNC_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = 0,
> +	}, {
> +		.id = MT8173_POWER_DOMAIN_USB,
> +		.name = "usb",
> +		.sta_mask = USB_PWR_STA_MASK,
> +		.ctl_offs = SPM_USB_PWR_CON,
> +		.sram_pdn_bits = GENMASK(11, 8),
> +		.sram_pdn_ack_bits = GENMASK(15, 12),
> +	},
> +};
> +
> +#define NUM_DOMAINS	ARRAY_SIZE(scp_domain_data)
> +
> +struct scp;
> +
> +struct scp_domain {
> +	struct generic_pm_domain pmd;
> +	struct scp_domain_data *data;
> +	struct scp *scp;
> +};
> +
> +struct scp {
> +	struct scp_domain domains[NUM_DOMAINS];
> +	struct generic_pm_domain *pmd[NUM_DOMAINS];
> +	struct genpd_onecell_data pd_data;
> +	void __iomem *base;
> +	struct regmap *infracfg;
> +};
> +
> +static int scpsys_power_on(struct generic_pm_domain *genpd)
> +{
> +	struct scp_domain *scpd = container_of(genpd, struct scp_domain, pmd);
> +	struct scp *scp = scpd->scp;
> +	struct scp_domain_data *data = scpd->data;
> +	unsigned long expired;
> +	void __iomem *ctl_addr = scpd->scp->base + data->ctl_offs;
> +	u32 sram_pdn_ack = data->sram_pdn_ack_bits;
> +	u32 val;
> +	int ret;
> +
> +	val = readl(ctl_addr);
> +	val |= PWR_ON_BIT;
> +	writel(val, ctl_addr);
> +	val |= PWR_ON_2ND_BIT;
> +	writel(val, ctl_addr);
> +
> +	/* wait until PWR_ACK = 1 */
> +	expired = jiffies + HZ;
> +	while (!(readl(scp->base + SPM_PWR_STATUS) & data->sta_mask) ||
> +			!(readl(scp->base + SPM_PWR_STATUS_2ND) & data->sta_mask)) {
> +		cpu_relax();
> +		if (time_after(jiffies, expired))
> +			return -EIO;

hmm, seems like you'd want a dev_warn() or simliar here if this times
out and fails.  There's a bunch of these below too.

> +	}
> +
> +	val &= ~PWR_CLK_DIS_BIT;
> +	writel(val, ctl_addr);
> +
> +	val &= ~PWR_ISO_BIT;
> +	writel(val, ctl_addr);
> +
> +	val |= PWR_RST_B_BIT;
> +	writel(val, ctl_addr);
> +
> +	val &= ~data->sram_pdn_bits;
> +	writel(val, ctl_addr);
> +
> +	/* wait until SRAM_PDN_ACK all 0 */
> +	expired = jiffies + HZ;
> +	while (sram_pdn_ack && (readl(ctl_addr) & sram_pdn_ack)) {
> +		cpu_relax();
> +		if (time_after(jiffies, expired))
> +			return -EIO;
> +	}
> +
> +	/* Clear bus protection bits */
> +	if (data->bus_prot_mask) {
> +		u32 mask = data->bus_prot_mask;
> +		struct regmap *infracfg = scp->infracfg;
> +
> +		regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, 0);
> +
> +		expired = jiffies + HZ;
> +
> +		while (1) {
> +			u32 val;
> +
> +			ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
> +			if (ret)
> +				return ret;
> +
> +			if (!(val & mask))
> +				break;
> +
> +			cpu_relax();
> +			if (time_after(jiffies, expired))
> +				return -EIO;
> +		}
> +	}

This whole "Clear bus protection bits" part seems like it should be an
API in the infracfg driver.

> +	return 0;
> +}
> +
> +static int scpsys_power_off(struct generic_pm_domain *genpd)
> +{
> +	struct scp_domain *scpd = container_of(genpd, struct scp_domain, pmd);
> +	struct scp *scp = scpd->scp;
> +	struct scp_domain_data *data = scpd->data;
> +	unsigned long expired;
> +	void __iomem *ctl_addr = scpd->scp->base + data->ctl_offs;
> +	u32 sram_pdn_ack = data->sram_pdn_ack_bits;
> +	u32 val;
> +	int ret;
> +
> +	/* set bus protection bits */
> +	if (data->bus_prot_mask) {
> +		struct regmap *infracfg = scp->infracfg;
> +		u32 mask = data->bus_prot_mask;
> +
> +		regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, mask);
> +
> +		expired = jiffies + HZ;
> +
> +		while (1) {
> +			ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
> +			if (ret)
> +				return ret;
> +
> +			if ((val & mask) == mask)
> +				break;
> +
> +			cpu_relax();
> +			if (time_after(jiffies, expired))
> +				return -EIO;
> +		}
> +	}

As with the 'clear bus protection bits', seems like this should be a
call into the infracfg driver.

> +	val = readl(ctl_addr);
> +	val |= data->sram_pdn_bits;
> +	writel(val, ctl_addr);
> +
> +	/* wait until SRAM_PDN_ACK all 1 */
> +	expired = jiffies + HZ;
> +	while ((readl(ctl_addr) & sram_pdn_ack) != sram_pdn_ack) {
> +		cpu_relax();
> +		if (time_after(jiffies, expired))
> +			return -EIO;
> +	}
> +
> +	val |= PWR_ISO_BIT;
> +	writel(val, ctl_addr);
> +
> +	val &= ~PWR_RST_B_BIT;
> +	writel(val, ctl_addr);
> +
> +	val |= PWR_CLK_DIS_BIT;
> +	writel(val, ctl_addr);
> +
> +	val &= ~PWR_ON_BIT;
> +	writel(val, ctl_addr);
> +
> +	val &= ~PWR_ON_2ND_BIT;
> +	writel(val, ctl_addr);
> +
> +	/* wait until PWR_ACK = 0 */
> +	expired = jiffies + HZ;
> +	while ((readl(scp->base + SPM_PWR_STATUS) & data->sta_mask) ||
> +			(readl(scp->base + SPM_PWR_STATUS_2ND) & data->sta_mask)) {
> +		cpu_relax();
> +		if (time_after(jiffies, expired))
> +			return -EIO;
> +	}
> +
> +	return 0;
> +}
> +
> +static int scpsys_probe(struct platform_device *pdev)
> +{
> +	struct genpd_onecell_data *pd_data;
> +	struct resource *res;
> +	int i;
> +	struct scp *scp = devm_kzalloc(&pdev->dev, sizeof(*scp), GFP_KERNEL);

This might return NULL...

> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	scp->base = devm_ioremap_resource(&pdev->dev, res);

... and, boom.

> +	if (IS_ERR(scp->base))
> +		return PTR_ERR(scp->base);
> +
> +	pd_data = &scp->pd_data;
> +
> +	scp->infracfg = syscon_regmap_lookup_by_compatible("mediatek,mt8173-infracfg");
> +	if (IS_ERR(scp->infracfg))
> +		return PTR_ERR(scp->infracfg);
> +
> +	pd_data->domains = scp->pmd;
> +	pd_data->num_domains = NUM_DOMAINS;
> +
> +	for (i = 0; i < NUM_DOMAINS; i++) {
> +		struct scp_domain *scpd = &scp->domains[i];
> +		struct generic_pm_domain *pmd = &scpd->pmd;
> +
> +		scp->pmd[i] = pmd;
> +		scpd->data = &scp_domain_data[i];
> +		scpd->scp = scp;
> +
> +		pmd->name = scp_domain_data[i].name;
> +		pmd->power_off = scpsys_power_off;
> +		pmd->power_on = scpsys_power_on;
> +		pmd->power_off_latency_ns = 20000;
> +		pmd->power_on_latency_ns = 20000;

Are the latencies for all domains really the same?   Seems like the
latencies should be part of the per-domain data.

Where did these numbers come from?  HW specs, measurement, etc?

Also, eventually, these latencies can (and should) come from DT
after the support from Geert[1] is merged, so putting them in the data
struct for now

> +		pd_data->domains[i] = pmd;
> +		pm_genpd_init(pmd, NULL, 1);
> +	}
> +
> +	return of_genpd_add_provider_onecell(pdev->dev.of_node, pd_data);
> +}
> +
> +static struct of_device_id of_scpsys_match_tbl[] = {
> +	{
> +		.compatible = "mediatek,mt8173-scpsys",
> +	}, {
> +		/* sentinel */
> +	}
> +};
> +MODULE_DEVICE_TABLE(of, of_scpsys_match_tbl);
> +
> +static struct platform_driver scpsys_drv = {
> +	.driver = {
> +		.name = "mtk-scpsys",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_match_ptr(of_scpsys_match_tbl),
> +	},
> +	.probe = scpsys_probe,
> +};
> +
> +module_platform_driver(scpsys_drv);

Kevin

[1] https://lkml.org/lkml/2014/11/17/270
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