linux-kernel - [PATCH 7/8] soc: mediatek: Add support for MTK_SCPD_STRICT_BUS

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Message-Id: <20230105170735.1637416-8-msp@baylibre.com>
Date:   Thu,  5 Jan 2023 18:07:34 +0100
From:   Markus Schneider-Pargmann <msp@...libre.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Matthias Brugger <matthias.bgg@...il.com>
Cc:     Chun-Jie Chen <chun-jie.chen@...iatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>,
        Fabien Parent <parent.f@...il.com>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Alexandre Bailon <abailon@...libre.com>,
        Fabien Parent <fparent@...libre.com>,
        Markus Schneider-Pargmann <msp@...libre.com>
Subject: [PATCH 7/8] soc: mediatek: Add support for MTK_SCPD_STRICT_BUS_PROTECTION cap

From: Alexandre Bailon <abailon@...libre.com>

This adds support for MTK_SCPD_STRICT_BUS_PROTECTION capability. It is a
strict bus protection policy that requires the bus protection to be
disabled before accessing the bus.
This is required by the mt8365, for the MM power domain.

Signed-off-by: Alexandre Bailon <abailon@...libre.com>
Signed-off-by: Fabien Parent <fparent@...libre.com>
Signed-off-by: Markus Schneider-Pargmann <msp@...libre.com>
---

Notes:
    Changes in v4:
    - Change name in title and commit message
    
    Changes in v3:
    - Rename MTK_SCPD_STRICT_BUSP to MTK_SCPD_STRICT_BUS_PROTECTION
    - Remove extra bool variable reflecting the capability
    
    Changes in v2:
    - Fixup error handling path.

 drivers/soc/mediatek/mtk-pm-domains.c | 27 +++++++++++++++++++++++----
 drivers/soc/mediatek/mtk-pm-domains.h |  1 +
 2 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/soc/mediatek/mtk-pm-domains.c b/drivers/soc/mediatek/mtk-pm-domains.c
index d53309f050ee..29a9028dd9b3 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.c
+++ b/drivers/soc/mediatek/mtk-pm-domains.c
@@ -265,9 +265,17 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	regmap_clear_bits(scpsys->base, pd->data->ctl_offs, PWR_ISO_BIT);
 	regmap_set_bits(scpsys->base, pd->data->ctl_offs, PWR_RST_B_BIT);
 
-	ret = clk_bulk_prepare_enable(pd->num_subsys_clks, pd->subsys_clks);
-	if (ret)
-		goto err_pwr_ack;
+	/*
+	 * In few Mediatek platforms(e.g. MT6779), the bus protect policy is
+	 * stricter, which leads to bus protect release must be prior to bus
+	 * access.
+	 */
+	if (!MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION)) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_pwr_ack;
+	}
 
 	ret = scpsys_sram_enable(pd);
 	if (ret < 0)
@@ -277,12 +285,23 @@ static int scpsys_power_on(struct generic_pm_domain *genpd)
 	if (ret < 0)
 		goto err_disable_sram;
 
+	if (MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION)) {
+		ret = clk_bulk_prepare_enable(pd->num_subsys_clks,
+					      pd->subsys_clks);
+		if (ret)
+			goto err_enable_bus_protect;
+	}
+
 	return 0;
 
+err_enable_bus_protect:
+	scpsys_bus_protect_enable(pd);
 err_disable_sram:
 	scpsys_sram_disable(pd);
 err_disable_subsys_clks:
-	clk_bulk_disable_unprepare(pd->num_subsys_clks, pd->subsys_clks);
+	if (!MTK_SCPD_CAPS(pd, MTK_SCPD_STRICT_BUS_PROTECTION))
+		clk_bulk_disable_unprepare(pd->num_subsys_clks,
+					   pd->subsys_clks);
 err_pwr_ack:
 	clk_bulk_disable_unprepare(pd->num_clks, pd->clks);
 err_reg:
diff --git a/drivers/soc/mediatek/mtk-pm-domains.h b/drivers/soc/mediatek/mtk-pm-domains.h
index 1fa634509db1..e5aa2348a9db 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.h
+++ b/drivers/soc/mediatek/mtk-pm-domains.h
@@ -11,6 +11,7 @@
 /* can't set MTK_SCPD_KEEP_DEFAULT_OFF at the same time */
 #define MTK_SCPD_ALWAYS_ON		BIT(5)
 #define MTK_SCPD_HAS_WAY_EN		BIT(6)
+#define MTK_SCPD_STRICT_BUS_PROTECTION	BIT(7)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210
-- 
2.39.0