[PATCH v4 1/5] dt-bindings: clock: gcc-msm8998: Add definitions of SSC-related clocks

[PATCH v4 1/5] dt-bindings: clock: gcc-msm8998: Add definitions of SSC-related clocks

[michael.srba]

From: Michael Srba <Michael.Srba@seznam.cz>

This patch adds definitions of four clocks which need to be manipulated
in order to initialize the AHB bus which exposes the SCC block in the
global address space.

Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
---
 CHANGES:
 - v2: none
 - v3: none
 - v4: none
---
 include/dt-bindings/clock/qcom,gcc-msm8998.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/dt-bindings/clock/qcom,gcc-msm8998.h b/include/dt-bindings/clock/qcom,gcc-msm8998.h
index 72c99e486d86..1badb4f9c58f 100644
--- a/include/dt-bindings/clock/qcom,gcc-msm8998.h
+++ b/include/dt-bindings/clock/qcom,gcc-msm8998.h
@@ -186,6 +186,10 @@
 #define UFS_UNIPRO_CORE_CLK_SRC					177
 #define GCC_MMSS_GPLL0_CLK					178
 #define HMSS_GPLL0_CLK_SRC					179
+#define GCC_IM_SLEEP						180
+#define AGGRE2_SNOC_NORTH_AXI					181
+#define SSC_XO							182
+#define SSC_CNOC_AHBS_CLK					183
 
 #define PCIE_0_GDSC						0
 #define UFS_GDSC						1
-- 
2.34.1

[PATCH v4 2/5] clk: qcom: gcc-msm8998: add SSC-related clocks

[michael.srba]

From: Michael Srba <Michael.Srba@seznam.cz>

This patch adds four clocks which need to be manipulated in order to
initialize the AHB bus which exposes the SCC block in the global address
space.

If a device is known to be configured such that writing to these
registers from Linux is not permitted, the 'protected-clocks'
device tree property must be used to denote that fact.

Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
---
 CHANGES:
 - v2: none
 - v3: none
 - v4: reword the commit message
---
 drivers/clk/qcom/gcc-msm8998.c | 56 ++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/clk/qcom/gcc-msm8998.c b/drivers/clk/qcom/gcc-msm8998.c
index 407e2c5caea4..2d14c3d672fc 100644
--- a/drivers/clk/qcom/gcc-msm8998.c
+++ b/drivers/clk/qcom/gcc-msm8998.c
@@ -2833,6 +2833,58 @@ static struct clk_branch gcc_rx1_usb2_clkref_clk = {
 	},
 };
 
+static struct clk_branch gcc_im_sleep_clk = {
+	.halt_reg = 0x4300C,
+	.halt_check = BRANCH_HALT,
+	.clkr = {
+		.enable_reg = 0x4300C,
+		.enable_mask = BIT(0),
+		.hw.init = &(struct clk_init_data){
+			.name = "gcc_im_sleep_clk",
+			.ops = &clk_branch2_ops,
+		},
+	},
+};
+
+static struct clk_branch aggre2_snoc_north_axi_clk = {
+	.halt_reg = 0x83010,
+	.halt_check = BRANCH_HALT,
+	.clkr = {
+		.enable_reg = 0x83010,
+		.enable_mask = BIT(0),
+		.hw.init = &(struct clk_init_data){
+			.name = "aggre2_snoc_north_axi_clk",
+			.ops = &clk_branch2_ops,
+		},
+	},
+};
+
+static struct clk_branch ssc_xo_clk = {
+	.halt_reg = 0x63018,
+	.halt_check = BRANCH_HALT,
+	.clkr = {
+		.enable_reg = 0x63018,
+		.enable_mask = BIT(0),
+		.hw.init = &(struct clk_init_data){
+			.name = "ssc_xo_clk",
+			.ops = &clk_branch2_ops,
+		},
+	},
+};
+
+static struct clk_branch ssc_cnoc_ahbs_clk = {
+	.halt_reg = 0x6300C,
+	.halt_check = BRANCH_HALT,
+	.clkr = {
+		.enable_reg = 0x6300C,
+		.enable_mask = BIT(0),
+		.hw.init = &(struct clk_init_data){
+			.name = "ssc_cnoc_ahbs_clk",
+			.ops = &clk_branch2_ops,
+		},
+	},
+};
+
 static struct gdsc pcie_0_gdsc = {
 	.gdscr = 0x6b004,
 	.gds_hw_ctrl = 0x0,
@@ -3036,6 +3088,10 @@ static struct clk_regmap *gcc_msm8998_clocks[] = {
 	[GCC_MSS_MNOC_BIMC_AXI_CLK] = &gcc_mss_mnoc_bimc_axi_clk.clkr,
 	[GCC_MMSS_GPLL0_CLK] = &gcc_mmss_gpll0_clk.clkr,
 	[HMSS_GPLL0_CLK_SRC] = &hmss_gpll0_clk_src.clkr,
+	[GCC_IM_SLEEP] = &gcc_im_sleep_clk.clkr,
+	[AGGRE2_SNOC_NORTH_AXI] = &aggre2_snoc_north_axi_clk.clkr,
+	[SSC_XO] = &ssc_xo_clk.clkr,
+	[SSC_CNOC_AHBS_CLK] = &ssc_cnoc_ahbs_clk.clkr,
 };
 
 static struct gdsc *gcc_msm8998_gdscs[] = {
-- 
2.34.1

[PATCH v4 3/5] dt-bindings: bus: add device tree bindings for qcom,ssc-block-bus

[michael.srba]

From: Michael Srba <Michael.Srba@seznam.cz>

This patch adds bindings for the AHB bus which exposes the SCC block in
the global address space. This bus (and the SSC block itself) is present
on certain qcom SoCs.

In typical configuration, this bus (as some of the clocks and registers
that we need to manipulate) is not accessible to the OS, and the
resources on this bus are indirectly accessed by communicating with a
hexagon CPU core residing in the SSC block. In this configuration, the
hypervisor is the one performing the bus initialization for the purposes
of bringing the haxagon CPU core out of reset.

However, it is possible to change the configuration, in which case this
binding serves to allow the OS to initialize the bus.

Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
---
 CHANGES:
 - v2: fix issues caught by by dt-schema
 - v3: none
 - v4: address the issues pointed out in the review
---
 .../bindings/bus/qcom,ssc-block-bus.yaml      | 150 ++++++++++++++++++
 1 file changed, 150 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml

diff --git a/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml b/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
new file mode 100644
index 000000000000..4bde169b1a19
--- /dev/null
+++ b/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
@@ -0,0 +1,150 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/bus/qcom,ssc-block-bus.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: The AHB Bus Providing a Global View of the SSC Block on (some) qcom SoCs
+
+maintainers:
+  - Michael Srba <Michael.Srba@seznam.cz>
+
+description: |
+  This binding describes the dependencies (clocks, resets, power domains) which
+  need to be turned on in a sequence before communication over the AHB bus
+  becomes possible.
+
+  Additionally, the reg property is used to pass to the driver the location of
+  two sadly undocumented registers which need to be poked as part of the sequence.
+
+properties:
+  compatible:
+    items:
+      - const: qcom,msm8998-ssc-block-bus
+      - const: qcom,ssc-block-bus
+
+  reg:
+    description: |
+      Shall contain the addresses of the SSCAON_CONFIG0 and SSCAON_CONFIG1
+      registers
+    minItems: 2
+    maxItems: 2
+
+  reg-names:
+    items:
+      - const: mpm_sscaon_config0
+      - const: mpm_sscaon_config1
+
+  '#address-cells':
+    enum: [ 1, 2 ]
+
+  '#size-cells':
+    enum: [ 1, 2 ]
+
+  ranges: true
+
+  clocks:
+    minItems: 6
+    maxItems: 6
+
+  clock-names:
+    items:
+      - const: xo
+      - const: aggre2
+      - const: gcc_im_sleep
+      - const: aggre2_north
+      - const: ssc_xo
+      - const: ssc_ahbs
+
+  power-domains:
+    description: Power domain phandles for the ssc_cx and ssc_mx power domains
+    minItems: 2
+    maxItems: 2
+
+  power-domain-names:
+    items:
+      - const: ssc_cx
+      - const: ssc_mx
+
+  resets:
+    description: |
+      Reset phandles for the ssc_reset and ssc_bcr resets (note: ssc_bcr is the
+      branch control register associated with the ssc_xo and ssc_ahbs clocks)
+    minItems: 2
+    maxItems: 2
+
+  reset-names:
+    items:
+      - const: ssc_reset
+      - const: ssc_bcr
+
+  qcom,halt-regs:
+    $ref: /schemas/types.yaml#/definitions/phandle-array
+    description: describes how to locate the ssc AXI halt register
+    items:
+      - items:
+        - description: Phandle reference to a syscon representing TCSR
+        - description: offset for the ssc AXI halt register
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - '#address-cells'
+  - '#size-cells'
+  - ranges
+  - clocks
+  - clock-names
+  - power-domains
+  - power-domain-names
+  - resets
+  - reset-names
+  - qcom,halt-regs
+
+additionalProperties: true
+
+examples:
+  - |
+    #include <dt-bindings/clock/qcom,gcc-msm8998.h>
+    #include <dt-bindings/clock/qcom,rpmcc.h>
+    #include <dt-bindings/power/qcom-rpmpd.h>
+
+    soc {
+        #address-cells = <1>;
+        #size-cells = <1>;
+
+        // devices under this node are physically located in the SSC block, connected to an ssc-internal bus;
+        ssc_ahb_slave: bus@10ac008 {
+            #address-cells = <1>;
+            #size-cells = <1>;
+            ranges;
+
+            compatible = "qcom,msm8998-ssc-block-bus", "qcom,ssc-block-bus";
+            reg = <0x10ac008 0x4>, <0x10ac010 0x4>;
+            reg-names = "mpm_sscaon_config0", "mpm_sscaon_config1";
+
+            clocks = <&xo>,
+                     <&rpmcc RPM_SMD_AGGR2_NOC_CLK>,
+                     <&gcc GCC_IM_SLEEP>,
+                     <&gcc AGGRE2_SNOC_NORTH_AXI>,
+                     <&gcc SSC_XO>,
+                     <&gcc SSC_CNOC_AHBS_CLK>;
+            clock-names = "xo", "aggre2", "gcc_im_sleep", "aggre2_north", "ssc_xo", "ssc_ahbs";
+
+            resets = <&gcc GCC_SSC_RESET>, <&gcc GCC_SSC_BCR>;
+            reset-names = "ssc_reset", "ssc_bcr";
+
+            power-domains = <&rpmpd MSM8998_SSCCX>, <&rpmpd MSM8998_SSCMX>;
+            power-domain-names = "ssc_cx", "ssc_mx";
+
+            qcom,halt-regs = <&tcsr_mutex_regs 0x26000>;
+
+            ssc_tlmm: pinctrl@5e10000 {
+                compatible = "qcom,msm8998-ssc-tlmm-pinctrl";
+                reg = <0x5E10000 0x10000>;
+                gpio-controller;
+                #gpio-cells = <2>;
+                gpio-ranges = <&ssc_tlmm 0 0 20>;
+            };
+        };
+    };
-- 
2.34.1

[PATCH v4 4/5] drivers: bus: add driver for initializing the SSC bus on (some) qcom SoCs

[michael.srba]

From: Michael Srba <Michael.Srba@seznam.cz>

This patch adds bindings for the AHB bus which exposes the SCC block in
the global address space. This bus (and the SSC block itself) is present
on certain qcom SoCs.

In typical configuration, this bus (as some of the clocks and registers
that we need to manipulate) is not accessible to Linux, and the resources
on this bus are indirectly accessed by communicating with a hexagon CPU
core residing in the SSC block. In this configuration, the hypervisor is
the one performing the bus initialization for the purposes of bringing
the haxagon CPU core out of reset.

However, it is possible to change the configuration, in which case this
driver will initialize the bus.

In combination with drivers for resources on the SSC bus, this driver can
aid in debugging, and for example with a TLMM driver can be used to
directly access SSC-dedicated GPIO pins, removing the need to commit
to a particular usecase during hw design.

Finally, until open firmware for the hexagon core is available, this
approach allows for using sensors hooked up to SSC-dedicated GPIO pins
on mainline Linux simply by utilizing the existing in-tree drivers for
these sensors.

Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
---
 CHANGES:
 - v2: none
 - v3: fix clang warning
 - v4: address the issues pointed out in the review
---
 drivers/bus/Kconfig              |   6 +
 drivers/bus/Makefile             |   1 +
 drivers/bus/qcom-ssc-block-bus.c | 383 +++++++++++++++++++++++++++++++
 3 files changed, 390 insertions(+)
 create mode 100644 drivers/bus/qcom-ssc-block-bus.c

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 3c68e174a113..f2b2e3098491 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -173,6 +173,12 @@ config SUNXI_RSB
 	  with various RSB based devices, such as AXP223, AXP8XX PMICs,
 	  and AC100/AC200 ICs.
 
+config QCOM_SSC_BLOCK_BUS
+	bool "Qualcomm SSC Block Bus Init Driver"
+	  help
+	  Say y here to enable support for initializing the bus that connects the SSC block's internal
+	  bus to the cNoC on (some) qcom SoCs
+
 config TEGRA_ACONNECT
 	tristate "Tegra ACONNECT Bus Driver"
 	depends on ARCH_TEGRA_210_SOC
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 52c2f35a26a9..e6756e83a9c4 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_OMAP_INTERCONNECT)	+= omap_l3_smx.o omap_l3_noc.o
 
 obj-$(CONFIG_OMAP_OCP2SCP)	+= omap-ocp2scp.o
 obj-$(CONFIG_QCOM_EBI2)		+= qcom-ebi2.o
+obj-$(CONFIG_QCOM_SSC_BLOCK_BUS)	+= qcom-ssc-block-bus.o
 obj-$(CONFIG_SUN50I_DE2_BUS)	+= sun50i-de2.o
 obj-$(CONFIG_SUNXI_RSB)		+= sunxi-rsb.o
 obj-$(CONFIG_OF)		+= simple-pm-bus.o
diff --git a/drivers/bus/qcom-ssc-block-bus.c b/drivers/bus/qcom-ssc-block-bus.c
new file mode 100644
index 000000000000..e489f5614e90
--- /dev/null
+++ b/drivers/bus/qcom-ssc-block-bus.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0-only
+// Copyright (c) 2021, Michael Srba
+
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_clock.h>
+#include <linux/pm_domain.h>
+#include <linux/pm_runtime.h>
+#include <linux/regmap.h>
+#include <linux/reset.h>
+
+/* AXI Halt Register Offsets */
+#define AXI_HALTREQ_REG			0x0
+#define AXI_HALTACK_REG			0x4
+#define AXI_IDLE_REG			0x8
+
+static const char *const qcom_ssc_block_pd_names[] = {
+	"ssc_cx",
+	"ssc_mx"
+};
+
+struct qcom_ssc_block_bus_data {
+	int num_pds;
+	const char *const *pd_names;
+	struct device *pds[ARRAY_SIZE(qcom_ssc_block_pd_names)];
+	char __iomem *reg_mpm_sscaon_config0; // MPM - msm power manager; AON - always-on
+	char __iomem *reg_mpm_sscaon_config1; // that's as much as we know about these
+	struct regmap *halt_map;
+	u32 ssc_axi_halt;
+	struct clk *xo_clk;
+	struct clk *aggre2_clk;
+	struct clk *gcc_im_sleep_clk;
+	struct clk *aggre2_north_clk;
+	struct clk *ssc_xo_clk;
+	struct clk *ssc_ahbs_clk;
+	struct reset_control *ssc_bcr;
+	struct reset_control *ssc_reset;
+};
+
+static void reg32_set_bits(char __iomem *reg, u32 value)
+{
+	u32 tmp = ioread32(reg);
+
+	iowrite32(tmp | value, reg);
+}
+
+static void reg32_clear_bits(char __iomem *reg, u32 value)
+{
+	u32 tmp = ioread32(reg);
+
+	iowrite32(tmp & (~value), reg);
+}
+
+
+static int qcom_ssc_block_bus_init(struct device *dev)
+{
+	int ret;
+
+	struct qcom_ssc_block_bus_data *data = dev_get_drvdata(dev);
+
+	ret = clk_prepare_enable(data->xo_clk);
+	if (ret) {
+		dev_err(dev, "error enabling xo_clk: %d\n", ret);
+		goto err_xo_clk;
+	}
+
+	ret = clk_prepare_enable(data->aggre2_clk);
+	if (ret) {
+		dev_err(dev, "error enabling aggre2_clk: %d\n", ret);
+		goto err_aggre2_clk;
+	}
+
+	ret = clk_prepare_enable(data->gcc_im_sleep_clk);
+	if (ret) {
+		dev_err(dev, "error enabling gcc_im_sleep_clk: %d\n", ret);
+		goto err_gcc_im_sleep_clk;
+	}
+
+	reg32_clear_bits(data->reg_mpm_sscaon_config0, BIT(4) | BIT(5));
+	reg32_clear_bits(data->reg_mpm_sscaon_config1, BIT(31));
+
+	ret = clk_prepare_enable(data->aggre2_north_clk);
+	if (ret) {
+		dev_err(dev, "error enabling aggre2_north_clk: %d\n", ret);
+		goto err_aggre2_north_clk;
+	}
+
+	ret = reset_control_deassert(data->ssc_reset);
+	if (ret) {
+		dev_err(dev, "error deasserting ssc_reset: %d\n", ret);
+		goto err_ssc_reset;
+	}
+
+	ret = reset_control_deassert(data->ssc_bcr);
+	if (ret) {
+		dev_err(dev, "error deasserting ssc_bcr: %d\n", ret);
+		goto err_ssc_bcr;
+	}
+
+	regmap_write(data->halt_map, data->ssc_axi_halt + AXI_HALTREQ_REG, 0);
+
+	ret = clk_prepare_enable(data->ssc_xo_clk);
+	if (ret) {
+		dev_err(dev, "error deasserting ssc_xo_clk: %d\n", ret);
+		goto err_ssc_xo_clk;
+	}
+
+	ret = clk_prepare_enable(data->ssc_ahbs_clk);
+	if (ret) {
+		dev_err(dev, "error deasserting ssc_ahbs_clk: %d\n", ret);
+		goto err_ssc_ahbs_clk;
+	}
+
+	return 0;
+
+err_ssc_ahbs_clk:
+	clk_disable(data->ssc_xo_clk);
+
+err_ssc_xo_clk:
+	regmap_write(data->halt_map, data->ssc_axi_halt + AXI_HALTREQ_REG, 1);
+
+	reset_control_assert(data->ssc_bcr);
+
+err_ssc_bcr:
+	reset_control_assert(data->ssc_reset);
+
+err_ssc_reset:
+	clk_disable(data->aggre2_north_clk);
+
+err_aggre2_north_clk:
+	reg32_set_bits(data->reg_mpm_sscaon_config0, BIT(4) | BIT(5));
+	reg32_set_bits(data->reg_mpm_sscaon_config1, BIT(31));
+
+	clk_disable(data->gcc_im_sleep_clk);
+
+err_gcc_im_sleep_clk:
+	clk_disable(data->aggre2_clk);
+
+err_aggre2_clk:
+	clk_disable(data->xo_clk);
+
+err_xo_clk:
+	return ret;
+}
+
+static void qcom_ssc_block_bus_deinit(struct device *dev)
+{
+	int ret;
+
+	struct qcom_ssc_block_bus_data *data = dev_get_drvdata(dev);
+
+	clk_disable(data->ssc_xo_clk);
+	clk_disable(data->ssc_ahbs_clk);
+
+	ret = reset_control_assert(data->ssc_bcr);
+	if (ret)
+		dev_err(dev, "error asserting ssc_bcr: %d\n", ret);
+
+	regmap_write(data->halt_map, data->ssc_axi_halt + AXI_HALTREQ_REG, 1);
+
+	reg32_set_bits(data->reg_mpm_sscaon_config1, BIT(31));
+	reg32_set_bits(data->reg_mpm_sscaon_config0, BIT(4) | BIT(5));
+
+	ret = reset_control_assert(data->ssc_reset);
+	if (ret)
+		dev_err(dev, "error asserting ssc_reset: %d\n", ret);
+
+	clk_disable(data->gcc_im_sleep_clk);
+
+	clk_disable(data->aggre2_north_clk);
+
+	clk_disable(data->aggre2_clk);
+	clk_disable(data->xo_clk);
+}
+
+
+static int qcom_ssc_block_bus_pds_attach(struct device *dev, struct device **pds,
+					 const char *const *pd_names, size_t num_pds)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_pds; i++) {
+		pds[i] = dev_pm_domain_attach_by_name(dev, pd_names[i]);
+		if (IS_ERR_OR_NULL(pds[i])) {
+			ret = PTR_ERR(pds[i]) ? : -ENODATA;
+			goto unroll_attach;
+		}
+	}
+
+	return num_pds;
+
+unroll_attach:
+	for (i--; i >= 0; i--)
+		dev_pm_domain_detach(pds[i], false);
+
+	return ret;
+};
+
+static void qcom_ssc_block_bus_pds_detach(struct device *dev, struct device **pds, size_t num_pds)
+{
+	int i;
+
+	for (i = 0; i < num_pds; i++)
+		dev_pm_domain_detach(pds[i], false);
+}
+
+static int qcom_ssc_block_bus_pds_enable(struct device **pds, size_t num_pds)
+{
+	int ret;
+	int i;
+
+	for (i = 0; i < num_pds; i++) {
+		dev_pm_genpd_set_performance_state(pds[i], INT_MAX);
+		ret = pm_runtime_get_sync(pds[i]);
+		if (ret < 0)
+			goto unroll_pd_votes;
+	}
+
+	return 0;
+
+unroll_pd_votes:
+	for (i--; i >= 0; i--) {
+		dev_pm_genpd_set_performance_state(pds[i], 0);
+		pm_runtime_put(pds[i]);
+	}
+
+	return ret;
+};
+
+static void qcom_ssc_block_bus_pds_disable(struct device **pds, size_t num_pds)
+{
+	int i;
+
+	for (i = 0; i < num_pds; i++) {
+		dev_pm_genpd_set_performance_state(pds[i], 0);
+		pm_runtime_put(pds[i]);
+	}
+}
+
+static int qcom_ssc_block_bus_probe(struct platform_device *pdev)
+{
+	struct qcom_ssc_block_bus_data *data;
+	struct device_node *np = pdev->dev.of_node;
+	struct of_phandle_args halt_args;
+	struct resource *res;
+	int ret;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, data);
+
+	data->pd_names = qcom_ssc_block_pd_names;
+	data->num_pds = ARRAY_SIZE(qcom_ssc_block_pd_names);
+
+	// power domains
+	ret = qcom_ssc_block_bus_pds_attach(&pdev->dev, data->pds, data->pd_names, data->num_pds);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "error when attaching power domains\n");
+
+	ret = qcom_ssc_block_bus_pds_enable(data->pds, data->num_pds);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "error when enabling power domains\n");
+
+	// the meaning of the bits in these two registers is sadly not documented,
+	// the set/clear operations are just copying what qcom does
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mpm_sscaon_config0");
+	data->reg_mpm_sscaon_config0 = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->reg_mpm_sscaon_config0))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->reg_mpm_sscaon_config0),
+				     "Failed to ioremap mpm_sscaon_config0\n");
+
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "mpm_sscaon_config1");
+	data->reg_mpm_sscaon_config1 = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->reg_mpm_sscaon_config1))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->reg_mpm_sscaon_config1),
+				     "Failed to ioremap mpm_sscaon_config1\n");
+
+	// resets
+	data->ssc_bcr = devm_reset_control_get_exclusive(&pdev->dev, "ssc_bcr");
+	if (IS_ERR(data->ssc_bcr))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->ssc_bcr),
+				     "Failed to acquire reset: scc_bcr\n");
+
+	data->ssc_reset = devm_reset_control_get_exclusive(&pdev->dev, "ssc_reset");
+	if (IS_ERR(data->ssc_reset))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->ssc_reset),
+				     "Failed to acquire reset: ssc_reset:\n");
+
+	// clocks
+	data->xo_clk = devm_clk_get(&pdev->dev, "xo");
+	if (IS_ERR(data->xo_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->xo_clk),
+				     "Failed to get clock: xo\n");
+
+	data->aggre2_clk = devm_clk_get(&pdev->dev, "aggre2");
+	if (IS_ERR(data->aggre2_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->aggre2_clk),
+				     "Failed to get clock: aggre2\n");
+
+	data->gcc_im_sleep_clk = devm_clk_get(&pdev->dev, "gcc_im_sleep");
+	if (IS_ERR(data->gcc_im_sleep_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->gcc_im_sleep_clk),
+				     "Failed to get clock: gcc_im_sleep\n");
+
+	data->aggre2_north_clk = devm_clk_get(&pdev->dev, "aggre2_north");
+	if (IS_ERR(data->aggre2_north_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->aggre2_north_clk),
+				     "Failed to get clock: aggre2_north\n");
+
+	data->ssc_xo_clk = devm_clk_get(&pdev->dev, "ssc_xo");
+	if (IS_ERR(data->ssc_xo_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->ssc_xo_clk),
+				     "Failed to get clock: ssc_xo\n");
+
+	data->ssc_ahbs_clk = devm_clk_get(&pdev->dev, "ssc_ahbs");
+	if (IS_ERR(data->ssc_ahbs_clk))
+		return dev_err_probe(&pdev->dev, PTR_ERR(data->ssc_ahbs_clk),
+				     "Failed to get clock: ssc_ahbs\n");
+
+	ret = of_parse_phandle_with_fixed_args(pdev->dev.of_node, "qcom,halt-regs", 1, 0,
+					       &halt_args);
+	if (ret < 0)
+		return dev_err_probe(&pdev->dev, ret, "Failed to parse qcom,halt-regs\n");
+
+	data->halt_map = syscon_node_to_regmap(halt_args.np);
+	of_node_put(halt_args.np);
+	if (IS_ERR(data->halt_map))
+		return PTR_ERR(data->halt_map);
+
+	data->ssc_axi_halt = halt_args.args[0];
+
+	qcom_ssc_block_bus_init(&pdev->dev);
+
+	of_platform_populate(np, NULL, NULL, &pdev->dev);
+
+	return 0;
+}
+
+static int qcom_ssc_block_bus_remove(struct platform_device *pdev)
+{
+	struct qcom_ssc_block_bus_data *data = platform_get_drvdata(pdev);
+
+	qcom_ssc_block_bus_deinit(&pdev->dev);
+
+	iounmap(data->reg_mpm_sscaon_config0);
+	iounmap(data->reg_mpm_sscaon_config1);
+
+	qcom_ssc_block_bus_pds_disable(data->pds, data->num_pds);
+	qcom_ssc_block_bus_pds_detach(&pdev->dev, data->pds, data->num_pds);
+	pm_runtime_disable(&pdev->dev);
+	pm_clk_destroy(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id qcom_ssc_block_bus_of_match[] = {
+	{ .compatible = "qcom,ssc-block-bus", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, qcom_ssc_block_bus_of_match);
+
+static struct platform_driver qcom_ssc_block_bus_driver = {
+	.probe = qcom_ssc_block_bus_probe,
+	.remove = qcom_ssc_block_bus_remove,
+	.driver = {
+		.name = "qcom-ssc-block-bus",
+		.of_match_table = qcom_ssc_block_bus_of_match,
+	},
+};
+
+module_platform_driver(qcom_ssc_block_bus_driver);
+
+MODULE_DESCRIPTION("A driver for handling the init sequence needed for accessing the SSC block on (some) qcom SoCs over AHB");
+MODULE_AUTHOR("Michael Srba <Michael.Srba@seznam.cz>");
+MODULE_LICENSE("GPL v2");
-- 
2.34.1

[PATCH v4 5/5] arm64: dts: qcom: msm8998: reserve potentially inaccessible clocks

[michael.srba]

From: Michael Srba <michael.srba@seznam.cz>

With the gcc driver now being more complete and describing clocks which
might not always be write-accessible to the OS, conservatively specify
all such clocks as protected in the SoC dts.
The board dts - or even user-supplied dts - can override this property
to reflect the actual configuration.

Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
---
 CHANGES:
 - v2: add this patch
 - v3: fix missing Signed-off-by
 - v4: add a proper explanation as per review, (hopefully) fix the subject and commit message
---
 arch/arm64/boot/dts/qcom/msm8998.dtsi | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/arch/arm64/boot/dts/qcom/msm8998.dtsi b/arch/arm64/boot/dts/qcom/msm8998.dtsi
index f273bc1ff629..16dccf9d881e 100644
--- a/arch/arm64/boot/dts/qcom/msm8998.dtsi
+++ b/arch/arm64/boot/dts/qcom/msm8998.dtsi
@@ -863,6 +863,21 @@ gcc: clock-controller@100000 {
 
 			clock-names = "xo", "sleep_clk";
 			clocks = <&xo>, <&sleep_clk>;
+
+			/*
+			 * The hypervisor typically configures the memory region where these clocks
+			 * reside as read-only for the HLOS. If the HLOS tried to enable or disable
+			 * these clocks on a device with such configuration (e.g. because they are
+			 * enabled but unused during boot-up), the device will most likely decide
+			 * to reboot.
+			 * In light of that, we are conservative here and we list all such clocks
+			 * as protected. The board dts (or a user-supplied dts) can override the
+			 * list of protected clocks if it differs from the norm, and it is in fact
+			 * desired for the HLOS to manage these clocks
+			 */
+			protected-clocks = <AGGRE2_SNOC_NORTH_AXI>,
+					   <SSC_XO>,
+					   <SSC_CNOC_AHBS_CLK>;
 		};
 
 		rpm_msg_ram: sram@778000 {
-- 
2.34.1

Re: [PATCH v4 3/5] dt-bindings: bus: add device tree bindings for qcom,ssc-block-bus

[Rob Herring]

On Wed, 26 Jan 2022 19:32:48 +0100, michael.srba@seznam.cz wrote:
> From: Michael Srba <Michael.Srba@seznam.cz>
> 
> This patch adds bindings for the AHB bus which exposes the SCC block in
> the global address space. This bus (and the SSC block itself) is present
> on certain qcom SoCs.
> 
> In typical configuration, this bus (as some of the clocks and registers
> that we need to manipulate) is not accessible to the OS, and the
> resources on this bus are indirectly accessed by communicating with a
> hexagon CPU core residing in the SSC block. In this configuration, the
> hypervisor is the one performing the bus initialization for the purposes
> of bringing the haxagon CPU core out of reset.
> 
> However, it is possible to change the configuration, in which case this
> binding serves to allow the OS to initialize the bus.
> 
> Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
> ---
>  CHANGES:
>  - v2: fix issues caught by by dt-schema
>  - v3: none
>  - v4: address the issues pointed out in the review
> ---
>  .../bindings/bus/qcom,ssc-block-bus.yaml      | 150 ++++++++++++++++++
>  1 file changed, 150 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:
./Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml:86:9: [warning] wrong indentation: expected 10 but found 8 (indentation)

dtschema/dtc warnings/errors:
Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.example.dt.yaml:0:0: /example-0/soc/bus@10ac008/pinctrl@5e10000: failed to match any schema with compatible: ['qcom,msm8998-ssc-tlmm-pinctrl']

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/1584622

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH v4 3/5] dt-bindings: bus: add device tree bindings for qcom,ssc-block-bus

[Rob Herring]

On Wed, Jan 26, 2022 at 07:32:48PM +0100, michael.srba@seznam.cz wrote:
> From: Michael Srba <Michael.Srba@seznam.cz>
> 
> This patch adds bindings for the AHB bus which exposes the SCC block in
> the global address space. This bus (and the SSC block itself) is present
> on certain qcom SoCs.
> 
> In typical configuration, this bus (as some of the clocks and registers
> that we need to manipulate) is not accessible to the OS, and the
> resources on this bus are indirectly accessed by communicating with a
> hexagon CPU core residing in the SSC block. In this configuration, the
> hypervisor is the one performing the bus initialization for the purposes
> of bringing the haxagon CPU core out of reset.
> 
> However, it is possible to change the configuration, in which case this
> binding serves to allow the OS to initialize the bus.
> 
> Signed-off-by: Michael Srba <Michael.Srba@seznam.cz>
> ---
>  CHANGES:
>  - v2: fix issues caught by by dt-schema
>  - v3: none
>  - v4: address the issues pointed out in the review
> ---
>  .../bindings/bus/qcom,ssc-block-bus.yaml      | 150 ++++++++++++++++++
>  1 file changed, 150 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
> 
> diff --git a/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml b/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
> new file mode 100644
> index 000000000000..4bde169b1a19
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/bus/qcom,ssc-block-bus.yaml
> @@ -0,0 +1,150 @@
> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/bus/qcom,ssc-block-bus.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: The AHB Bus Providing a Global View of the SSC Block on (some) qcom SoCs
> +
> +maintainers:
> +  - Michael Srba <Michael.Srba@seznam.cz>
> +
> +description: |
> +  This binding describes the dependencies (clocks, resets, power domains) which
> +  need to be turned on in a sequence before communication over the AHB bus
> +  becomes possible.
> +
> +  Additionally, the reg property is used to pass to the driver the location of
> +  two sadly undocumented registers which need to be poked as part of the sequence.
> +
> +properties:
> +  compatible:
> +    items:
> +      - const: qcom,msm8998-ssc-block-bus
> +      - const: qcom,ssc-block-bus
> +
> +  reg:
> +    description: |
> +      Shall contain the addresses of the SSCAON_CONFIG0 and SSCAON_CONFIG1
> +      registers
> +    minItems: 2
> +    maxItems: 2
> +
> +  reg-names:
> +    items:
> +      - const: mpm_sscaon_config0
> +      - const: mpm_sscaon_config1
> +
> +  '#address-cells':
> +    enum: [ 1, 2 ]
> +
> +  '#size-cells':
> +    enum: [ 1, 2 ]
> +
> +  ranges: true
> +
> +  clocks:
> +    minItems: 6
> +    maxItems: 6
> +
> +  clock-names:
> +    items:
> +      - const: xo
> +      - const: aggre2
> +      - const: gcc_im_sleep
> +      - const: aggre2_north
> +      - const: ssc_xo
> +      - const: ssc_ahbs
> +
> +  power-domains:
> +    description: Power domain phandles for the ssc_cx and ssc_mx power domains
> +    minItems: 2
> +    maxItems: 2
> +
> +  power-domain-names:
> +    items:
> +      - const: ssc_cx
> +      - const: ssc_mx
> +
> +  resets:
> +    description: |
> +      Reset phandles for the ssc_reset and ssc_bcr resets (note: ssc_bcr is the
> +      branch control register associated with the ssc_xo and ssc_ahbs clocks)
> +    minItems: 2
> +    maxItems: 2
> +
> +  reset-names:
> +    items:
> +      - const: ssc_reset
> +      - const: ssc_bcr
> +
> +  qcom,halt-regs:
> +    $ref: /schemas/types.yaml#/definitions/phandle-array
> +    description: describes how to locate the ssc AXI halt register
> +    items:
> +      - items:
> +        - description: Phandle reference to a syscon representing TCSR
> +        - description: offset for the ssc AXI halt register
> +
> +required:
> +  - compatible
> +  - reg
> +  - reg-names
> +  - '#address-cells'
> +  - '#size-cells'
> +  - ranges
> +  - clocks
> +  - clock-names
> +  - power-domains
> +  - power-domain-names
> +  - resets
> +  - reset-names
> +  - qcom,halt-regs
> +
> +additionalProperties: true

To say anything else should be a node:

additionalProperties:
  type: object

> +
> +examples:
> +  - |
> +    #include <dt-bindings/clock/qcom,gcc-msm8998.h>
> +    #include <dt-bindings/clock/qcom,rpmcc.h>
> +    #include <dt-bindings/power/qcom-rpmpd.h>
> +
> +    soc {
> +        #address-cells = <1>;
> +        #size-cells = <1>;
> +
> +        // devices under this node are physically located in the SSC block, connected to an ssc-internal bus;
> +        ssc_ahb_slave: bus@10ac008 {
> +            #address-cells = <1>;
> +            #size-cells = <1>;
> +            ranges;
> +
> +            compatible = "qcom,msm8998-ssc-block-bus", "qcom,ssc-block-bus";
> +            reg = <0x10ac008 0x4>, <0x10ac010 0x4>;
> +            reg-names = "mpm_sscaon_config0", "mpm_sscaon_config1";
> +
> +            clocks = <&xo>,
> +                     <&rpmcc RPM_SMD_AGGR2_NOC_CLK>,
> +                     <&gcc GCC_IM_SLEEP>,
> +                     <&gcc AGGRE2_SNOC_NORTH_AXI>,
> +                     <&gcc SSC_XO>,
> +                     <&gcc SSC_CNOC_AHBS_CLK>;
> +            clock-names = "xo", "aggre2", "gcc_im_sleep", "aggre2_north", "ssc_xo", "ssc_ahbs";
> +
> +            resets = <&gcc GCC_SSC_RESET>, <&gcc GCC_SSC_BCR>;
> +            reset-names = "ssc_reset", "ssc_bcr";
> +
> +            power-domains = <&rpmpd MSM8998_SSCCX>, <&rpmpd MSM8998_SSCMX>;
> +            power-domain-names = "ssc_cx", "ssc_mx";
> +
> +            qcom,halt-regs = <&tcsr_mutex_regs 0x26000>;
> +
> +            ssc_tlmm: pinctrl@5e10000 {
> +                compatible = "qcom,msm8998-ssc-tlmm-pinctrl";

If you don't want to define a schema for this, pick another node that 
has a schema already.

> +                reg = <0x5E10000 0x10000>;
> +                gpio-controller;
> +                #gpio-cells = <2>;
> +                gpio-ranges = <&ssc_tlmm 0 0 20>;
> +            };
> +        };
> +    };
> -- 
> 2.34.1
> 
>