bcm53xx: add temporary BCM53573 ILP clock driver

It wasn't accepted upstream as there was a discusson on Northstar vs.
BCM53573. Once we get a new ARM arch Kconfig entry it should be
possible to upstream it.

Signed-off-by: Rafał Miłecki <[email protected]>

target/linux/bcm53xx/patches-4.4/830-clk-bcm-Add-driver-for-Northstar-ILP-clock.patch

@@ -0,0 +1,235 @@
+From 65acc8219d271d29b918ae4d6fe4d520203f25ae Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <[email protected]>
+Date: Fri, 29 Jul 2016 14:48:19 +0200
+Subject: [PATCH V3] clk: bcm: Add driver for Northstar ILP clock
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+This clock is present on cheaper Northstar devices like BCM53573 or
+BCM47189 using Corex-A7. ILP is a part of PMU (Power Management Unit)
+and so it should be defined as one of its subnodes (subdevices). For
+more details see Documentation entry.
+
+Unfortunately there isn't a set of registers related to ILP clock only.
+We use registers 0x66c, 0x674 and 0x6dc and between them there are e.g.
+"retention*" and "control_ext" regs. This is why this driver maps all
+0x1000 B of space.
+
+Signed-off-by: Rafał Miłecki <[email protected]>
+---
+V2: Rebase on top of clk-next
+    Use ALP as parent clock
+    Improve comments
+    Switch from ioremap_nocache to ioremap
+    Check of_clk_add_provide result for error
+V3: Drop #include <linux/moduleh>
+    Make ILP DT entry part of PMU
+    Describe ILP as subdevice of PMU in Documentation
+---
+ .../devicetree/bindings/clock/brcm,ns-ilp.txt      |  40 ++++++
+ drivers/clk/bcm/Makefile                           |   1 +
+ drivers/clk/bcm/clk-ns-ilp.c                       | 146 +++++++++++++++++++++
+ 3 files changed, 187 insertions(+)
+ create mode 100644 Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
+ create mode 100644 drivers/clk/bcm/clk-ns-ilp.c
+
+--- /dev/null
++++ b/Documentation/devicetree/bindings/clock/brcm,ns-ilp.txt
+@@ -0,0 +1,40 @@
++Broadcom Northstar ILP clock
++============================
++
++This binding uses the common clock binding:
++    Documentation/devicetree/bindings/clock/clock-bindings.txt
++
++This binding is used for ILP clock (sometimes referred as "slow clock")
++on Broadcom Northstar devices using Corex-A7 CPU.
++
++This clock is part of PMU (Power Management Unit), a Broadcom's device
++handing power-related aspects. Please note PMU contains more subdevices,
++ILP is only one of them.
++
++ILP's rate has to be calculated on runtime and it depends on ALP clock
++which has to be referenced.
++
++Required properties:
++- compatible: "brcm,ns-ilp"
++- reg: iomem address range of PMU (Power Management Unit)
++- reg-names: "pmu", the only needed & supported reg right now
++- clocks: has to reference an ALP clock
++- #clock-cells: should be <0>
++
++Example:
++
++pmu@18012000 {
++	compatible = "simple-bus";
++	ranges = <0x00000000 0x18012000 0x00001000>;
++	#address-cells = <1>;
++	#size-cells = <1>;
++
++	ilp: ilp@0 {
++		compatible = "brcm,ns-ilp";
++		reg = <0 0x1000>;
++		reg-names = "pmu";
++		clocks = <&alp>;
++		#clock-cells = <0>;
++		clock-output-names = "ilp";
++	};
++};
+--- a/drivers/clk/bcm/Makefile
++++ b/drivers/clk/bcm/Makefile
+@@ -8,3 +8,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)	+= clk-ns
+ obj-$(CONFIG_ARCH_BCM_CYGNUS)	+= clk-cygnus.o
+ obj-$(CONFIG_ARCH_BCM_NSP)	+= clk-nsp.o
+ obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-nsp.o
++obj-$(CONFIG_ARCH_BCM_5301X)	+= clk-ns-ilp.o
+--- /dev/null
++++ b/drivers/clk/bcm/clk-ns-ilp.c
+@@ -0,0 +1,146 @@
++/*
++ * Copyright (C) 2016 Rafał Miłecki <[email protected]>
++ *
++ * 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.
++ */
++
++#include <linux/clk.h>
++#include <linux/clk-provider.h>
++#include <linux/err.h>
++#include <linux/io.h>
++#include <linux/of.h>
++#include <linux/of_address.h>
++#include <linux/slab.h>
++
++#define PMU_XTAL_FREQ_RATIO			0x66c
++#define  XTAL_ALP_PER_4ILP			0x00001fff
++#define  XTAL_CTL_EN				0x80000000
++#define PMU_SLOW_CLK_PERIOD			0x6dc
++
++struct ns_ilp {
++	struct clk *clk;
++	struct clk_hw hw;
++	void __iomem *pmu;
++};
++
++static int ns_ilp_enable(struct clk_hw *hw)
++{
++	struct ns_ilp *ilp = container_of(hw, struct ns_ilp, hw);
++
++	writel(0x10199, ilp->pmu + PMU_SLOW_CLK_PERIOD);
++	writel(0x10000, ilp->pmu + 0x674);
++
++	return 0;
++}
++
++static unsigned long ns_ilp_recalc_rate(struct clk_hw *hw,
++					unsigned long parent_rate)
++{
++	struct ns_ilp *ilp = container_of(hw, struct ns_ilp, hw);
++	void __iomem *pmu = ilp->pmu;
++	u32 last_val, cur_val;
++	u32 sum = 0, num = 0, loop_num = 0;
++	u32 avg;
++
++	/* Enable measurement */
++	writel(XTAL_CTL_EN, pmu + PMU_XTAL_FREQ_RATIO);
++
++	/* Read initial value */
++	last_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
++
++	/*
++	 * At minimum we should loop for a bit to let hardware do the
++	 * measurement. This isn't very accurate however, so for a better
++	 * precision lets try getting 20 different values for and use average.
++	 */
++	while (num < 20) {
++		cur_val = readl(pmu + PMU_XTAL_FREQ_RATIO) & XTAL_ALP_PER_4ILP;
++
++		if (cur_val != last_val) {
++			/* Got different value, use it */
++			sum += cur_val;
++			num++;
++			loop_num = 0;
++			last_val = cur_val;
++		} else if (++loop_num > 5000) {
++			/* Same value over and over, give up */
++			sum += cur_val;
++			num++;
++			break;
++		}
++	}
++
++	/* Disable measurement to save power */
++	writel(0x0, pmu + PMU_XTAL_FREQ_RATIO);
++
++	avg = sum / num;
++
++	return parent_rate * 4 / avg;
++}
++
++static const struct clk_ops ns_ilp_clk_ops = {
++	.enable = ns_ilp_enable,
++	.recalc_rate = ns_ilp_recalc_rate,
++};
++
++static void ns_ilp_init(struct device_node *np)
++{
++	struct ns_ilp *ilp;
++	struct resource res;
++	struct clk_init_data init = { 0 };
++	const char *parent_name;
++	int index;
++	int err;
++
++	ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
++	if (!ilp)
++		return;
++
++	parent_name = of_clk_get_parent_name(np, 0);
++	if (!parent_name) {
++		err = -ENOENT;
++		goto err_free_ilp;
++	}
++
++	/* TODO: This looks generic, try making it OF helper. */
++	index = of_property_match_string(np, "reg-names", "pmu");
++	if (index < 0) {
++		err = index;
++		goto err_free_ilp;
++	}
++	err = of_address_to_resource(np, index, &res);
++	if (err)
++		goto err_free_ilp;
++	ilp->pmu = ioremap(res.start, resource_size(&res));
++	if (IS_ERR(ilp->pmu)) {
++		err = PTR_ERR(ilp->pmu);
++		goto err_free_ilp;
++	}
++
++	init.name = np->name;
++	init.ops = &ns_ilp_clk_ops;
++	init.parent_names = &parent_name;
++	init.num_parents = 1;
++
++	ilp->hw.init = &init;
++	ilp->clk = clk_register(NULL, &ilp->hw);
++	if (WARN_ON(IS_ERR(ilp->clk)))
++		goto err_unmap_pmu;
++
++	err = of_clk_add_provider(np, of_clk_src_simple_get, ilp->clk);
++	if (err)
++		goto err_clk_unregister;
++
++	return;
++
++err_clk_unregister:
++	clk_unregister(ilp->clk);
++err_unmap_pmu:
++	iounmap(ilp->pmu);
++err_free_ilp:
++	kfree(ilp);
++	pr_err("Failed to init ILP clock: %d\n", err);
++}
++CLK_OF_DECLARE(ns_ilp_clk, "brcm,ns-ilp", ns_ilp_init);