[RFC PATCH v2 0/2] Syscon early initialization

[RFC PATCH v2 0/2] Syscon early initialization

[Michal Simek]

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Hi,

this series come from my discussion with Arnd at KS and then
on some other threads/IRCs(Arnd and Mark) that SoC vendors
are more and more try to add misc functionality to
one memory region. For this purpose syscon driver is in the kernel.
But regular syscon driver is initialized too late
and platforms are trying to create specific code to handle it.

For this purpose the series have been created to provide
early syscon initialization and regmap creation first
and then attaching device.

The last patch is zynq specific patch to clear slcr driver
and clock driver can profit from it too when clk regmap is ready.

Also moving syscon driver from mfs should be consider.

Mark already applied the first part to his regmap repo
git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git tags/nodev

Thanks for your comments,
Michal

Changes in v2:
- Fix bad logic in early_syscon_probe
- Fix compilation failure for x86_64 reported by zero day testing system
- Regmap change available here
  git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git tags/nodev

Michal Simek (2):
  mfd: syscon: Support early initialization
  ARM: zynq: Use early syscon initialization

 arch/arm/boot/dts/zynq-7000.dtsi |   1 +
 arch/arm/mach-zynq/common.c      |   6 +-
 arch/arm/mach-zynq/slcr.c        |  42 +------------
 drivers/clk/zynq/clkc.c          |  57 ++++++-----------
 drivers/mfd/syscon.c             | 128 +++++++++++++++++++++++++++++++++------
 include/linux/mfd/syscon.h       |  11 ++++
 6 files changed, 145 insertions(+), 100 deletions(-)

--
1.8.2.3


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[RFC PATCH v2 2/2] ARM: zynq: Use early syscon initialization

[Michal Simek]

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Use early syscon initialization to simplify slcr code.
- Remove two slcr inits (zynq_slcr_init, zynq_early_slcr_init)
- Directly use regmap accesses in zynq_slcr_read/write
- Remove zynq_clock_init() and use addresses from syscon
  (This is the most problematic part now because clock
  doesn't support regmap accesses that's why reading
  slcr base is ugly. There are some attempts to get
  clk regmap to work - for example:
  https://lkml.org/lkml/2013/10/16/112)

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
---

Changes in v2: None

Especially look at slcr.c which is much simpler than was before.
clkc.c will be simpler when regmap support is added because then
syscon_early_regmap_lookup_by_phandle() will be called
without zynq_slcr_base search.

---
 arch/arm/boot/dts/zynq-7000.dtsi |  1 +
 arch/arm/mach-zynq/common.c      |  6 ++---
 arch/arm/mach-zynq/slcr.c        | 42 ++---------------------------
 drivers/clk/zynq/clkc.c          | 57 ++++++++++++----------------------------
 4 files changed, 23 insertions(+), 83 deletions(-)

diff --git a/arch/arm/boot/dts/zynq-7000.dtsi b/arch/arm/boot/dts/zynq-7000.dtsi
index 7284499..e414489 100644
--- a/arch/arm/boot/dts/zynq-7000.dtsi
+++ b/arch/arm/boot/dts/zynq-7000.dtsi
@@ -135,6 +135,7 @@
 			compatible = "xlnx,zynq-slcr", "syscon";
 			reg = <0xF8000000 0x1000>;
 			ranges;
+			syscon = <&slcr>;
 			clkc: clkc@100 {
 				#clock-cells = <1>;
 				compatible = "xlnx,ps7-clkc";
diff --git a/arch/arm/mach-zynq/common.c b/arch/arm/mach-zynq/common.c
index 9d3c88e..78589e3 100644
--- a/arch/arm/mach-zynq/common.c
+++ b/arch/arm/mach-zynq/common.c
@@ -28,6 +28,7 @@
 #include <linux/of.h>
 #include <linux/irqchip.h>
 #include <linux/irqchip/arm-gic.h>
+#include <linux/mfd/syscon.h>
 #include <linux/slab.h>
 #include <linux/sys_soc.h>

@@ -130,15 +131,14 @@ out:
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, parent);

 	platform_device_register(&zynq_cpuidle_device);
-
-	zynq_slcr_init();
 }

 static void __init zynq_timer_init(void)
 {
+	early_syscon_init();
+
 	zynq_early_slcr_init();

-	zynq_clock_init();
 	of_clk_init(NULL);
 	clocksource_of_init();
 }
diff --git a/arch/arm/mach-zynq/slcr.c b/arch/arm/mach-zynq/slcr.c
index 594b280..a89b082 100644
--- a/arch/arm/mach-zynq/slcr.c
+++ b/arch/arm/mach-zynq/slcr.c
@@ -35,7 +35,6 @@
 #define SLCR_PSS_IDCODE_DEVICE_SHIFT	12
 #define SLCR_PSS_IDCODE_DEVICE_MASK	0x1F

-static void __iomem *zynq_slcr_base;
 static struct regmap *zynq_slcr_regmap;

 /**
@@ -48,11 +47,6 @@ static struct regmap *zynq_slcr_regmap;
  */
 static int zynq_slcr_write(u32 val, u32 offset)
 {
-	if (!zynq_slcr_regmap) {
-		writel(val, zynq_slcr_base + offset);
-		return 0;
-	}
-
 	return regmap_write(zynq_slcr_regmap, offset, val);
 }

@@ -66,12 +60,7 @@ static int zynq_slcr_write(u32 val, u32 offset)
  */
 static int zynq_slcr_read(u32 *val, u32 offset)
 {
-	if (zynq_slcr_regmap)
-		return regmap_read(zynq_slcr_regmap, offset, val);
-
-	*val = readl(zynq_slcr_base + offset);
-
-	return 0;
+	return regmap_read(zynq_slcr_regmap, offset, val);
 }

 /**
@@ -169,24 +158,6 @@ void zynq_slcr_cpu_stop(int cpu)
 }

 /**
- * zynq_slcr_init - Regular slcr driver init
- *
- * Return:	0 on success, negative errno otherwise.
- *
- * Called early during boot from platform code to remap SLCR area.
- */
-int __init zynq_slcr_init(void)
-{
-	zynq_slcr_regmap = syscon_regmap_lookup_by_compatible("xlnx,zynq-slcr");
-	if (IS_ERR(zynq_slcr_regmap)) {
-		pr_err("%s: failed to find zynq-slcr\n", __func__);
-		return -ENODEV;
-	}
-
-	return 0;
-}
-
-/**
  * zynq_early_slcr_init - Early slcr init function
  *
  * Return:	0 on success, negative errno otherwise.
@@ -202,20 +173,11 @@ int __init zynq_early_slcr_init(void)
 		pr_err("%s: no slcr node found\n", __func__);
 		BUG();
 	}
-
-	zynq_slcr_base = of_iomap(np, 0);
-	if (!zynq_slcr_base) {
-		pr_err("%s: Unable to map I/O memory\n", __func__);
-		BUG();
-	}
-
-	np->data = (__force void *)zynq_slcr_base;
+	zynq_slcr_regmap = syscon_early_regmap_lookup_by_phandle(np, "syscon");

 	/* unlock the SLCR so that registers can be changed */
 	zynq_slcr_unlock();

-	pr_info("%s mapped to %p\n", np->name, zynq_slcr_base);
-
 	of_node_put(np);

 	return 0;
diff --git a/drivers/clk/zynq/clkc.c b/drivers/clk/zynq/clkc.c
index c812b93..b2fd160 100644
--- a/drivers/clk/zynq/clkc.c
+++ b/drivers/clk/zynq/clkc.c
@@ -214,6 +214,10 @@ err:
 		clks[clk1] = ERR_PTR(-ENOMEM);
 }

+struct syscon {
+	void __iomem *base;
+};
+
 static void __init zynq_clk_setup(struct device_node *np)
 {
 	int i;
@@ -227,6 +231,19 @@ static void __init zynq_clk_setup(struct device_node *np)
 	const char *periph_parents[4];
 	const char *swdt_ext_clk_mux_parents[2];
 	const char *can_mio_mux_parents[NUM_MIO_PINS];
+	struct resource res;
+	void __iomem *zynq_slcr_base;
+
+	struct device_node *slcr = of_get_parent(np);
+	struct syscon *syscon = slcr->data;
+	zynq_slcr_base = syscon->base;
+
+	if (of_address_to_resource(np, 0, &res)) {
+		pr_err("%s: failed to get resource\n", np->name);
+		return;
+	}
+
+	zynq_clkc_base = zynq_slcr_base + res.start;

 	pr_info("Zynq clock init\n");

@@ -569,43 +586,3 @@ static void __init zynq_clk_setup(struct device_node *np)
 }

 CLK_OF_DECLARE(zynq_clkc, "xlnx,ps7-clkc", zynq_clk_setup);
-
-void __init zynq_clock_init(void)
-{
-	struct device_node *np;
-	struct device_node *slcr;
-	struct resource res;
-
-	np = of_find_compatible_node(NULL, NULL, "xlnx,ps7-clkc");
-	if (!np) {
-		pr_err("%s: clkc node not found\n", __func__);
-		goto np_err;
-	}
-
-	if (of_address_to_resource(np, 0, &res)) {
-		pr_err("%s: failed to get resource\n", np->name);
-		goto np_err;
-	}
-
-	slcr = of_get_parent(np);
-
-	if (slcr->data) {
-		zynq_clkc_base = (__force void __iomem *)slcr->data + res.start;
-	} else {
-		pr_err("%s: Unable to get I/O memory\n", np->name);
-		of_node_put(slcr);
-		goto np_err;
-	}
-
-	pr_info("%s: clkc starts at %p\n", __func__, zynq_clkc_base);
-
-	of_node_put(slcr);
-	of_node_put(np);
-
-	return;
-
-np_err:
-	of_node_put(np);
-	BUG();
-	return;
-}
--
1.8.2.3


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