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From:   Markus Schneider-Pargmann <msp@baylibre.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Chun-Jie Chen <chun-jie.chen@mediatek.com>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        Fabien Parent <parent.f@gmail.com>, devicetree@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mediatek@lists.infradead.org,
        Alexandre Bailon <abailon@baylibre.com>,
        Fabien Parent <fparent@baylibre.com>,
        Markus Schneider-Pargmann <msp@baylibre.com>
Subject: [PATCH v3 3/4] soc: mediatek: add support of MTK_SCPD_STRICT_BUSP cap
Date:   Mon, 22 Aug 2022 16:43:02 +0200
Message-Id: <20220822144303.3438467-4-msp@baylibre.com>
In-Reply-To: <20220822144303.3438467-1-msp@baylibre.com>
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From: Alexandre Bailon <abailon@baylibre.com>

This adds support for MTK_SCPD_STRICT_BUSP 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@baylibre.com>
Signed-off-by: Fabien Parent <fparent@baylibre.com>
Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
---

Notes:
    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 c2cbe0de6aa1..d323275aa11c 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.c
+++ b/drivers/soc/mediatek/mtk-pm-domains.c
@@ -303,9 +303,17 @@ 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)
@@ -315,12 +323,23 @@ 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 974c68a1d89c..493f3fa14612 100644
--- a/drivers/soc/mediatek/mtk-pm-domains.h
+++ b/drivers/soc/mediatek/mtk-pm-domains.h
@@ -10,6 +10,7 @@
 #define MTK_SCPD_DOMAIN_SUPPLY		BIT(4)
 /* can't set MTK_SCPD_KEEP_DEFAULT_OFF at the same time */
 #define MTK_SCPD_ALWAYS_ON		BIT(5)
+#define MTK_SCPD_STRICT_BUS_PROTECTION	BIT(6)
 #define MTK_SCPD_CAPS(_scpd, _x)	((_scpd)->data->caps & (_x))
 
 #define SPM_VDE_PWR_CON			0x0210
-- 
2.37.2