target/linux/bcm53xx/patches-4.4/830-clk-bcm-Add-driver-for-BCM53573-ILP-clock.patch

   1 From 205fc550ceb74f7e8bfcba5c5c7329aa1b34d4ee Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
   3 Date: Fri, 29 Jul 2016 14:48:19 +0200
   4 Subject: [PATCH V8] clk: bcm: Add driver for BCM53573 ILP clock
   5 MIME-Version: 1.0
   6 Content-Type: text/plain; charset=UTF-8
   7 Content-Transfer-Encoding: 8bit
   8
   9 This clock is present on BCM53573 devices (including BCM47189) that use
  10 Cortex-A7. ILP is a part of PMU (Power Management Unit) multi-function
  11 device so we use syscon (and regmap) for it.
  12
  13 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  14 ---
  15 V2: Rebase on top of clk-next
  16     Use ALP as parent clock
  17     Improve comments
  18     Switch from ioremap_nocache to ioremap
  19     Check of_clk_add_provide result for error
  20 V3: Drop #include <linux/moduleh>
  21     Make ILP DT entry part of PMU
  22     Describe ILP as subdevice of PMU in Documentation
  23 V4: Use BCM53573 name as suggested by Jon and Ray. It seems "Northstar"
  24     (even if used in some resources) should be used in relation to
  25     Cortex-A9 devices only.
  26 V5: Rename remaining "ns" references to "bcm53573", sorry, I sent V4 too
  27     early.
  28 V6: Drop #include <linux/clk.h>
  29     Use "int" as type where it matches usage
  30     Add cpu_relax() in the loop
  31     Add disable callback
  32     Use _hw_ functions for registering struct clk_hw (new API)
  33
  34     Thanks a lot Stephen!
  35 V7: Use syscon and regmap (thanks Rob!)
  36 V8: Update Documentation (drop unused "reg", unit address)
  37 ---
  38  .../bindings/clock/brcm,bcm53573-ilp.txt           |  36 +++++
  39  drivers/clk/bcm/Makefile                           |   1 +
  40  drivers/clk/bcm/clk-bcm53573-ilp.c                 | 148 +++++++++++++++++++++
  41  3 files changed, 185 insertions(+)
  42  create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
  43  create mode 100644 drivers/clk/bcm/clk-bcm53573-ilp.c
  44
  45 --- /dev/null
  46 +++ b/Documentation/devicetree/bindings/clock/brcm,bcm53573-ilp.txt
  47 @@ -0,0 +1,36 @@
  48 +Broadcom BCM53573 ILP clock
  49 +===========================
  50 +
  51 +This binding uses the common clock binding:
  52 +    Documentation/devicetree/bindings/clock/clock-bindings.txt
  53 +
  54 +This binding is used for ILP clock (sometimes referred as "slow clock")
  55 +on Broadcom BCM53573 devices using Cortex-A7 CPU.
  56 +
  57 +ILP's rate has to be calculated on runtime and it depends on ALP clock
  58 +which has to be referenced.
  59 +
  60 +This clock is part of PMU (Power Management Unit), a Broadcom's device
  61 +handing power-related aspects. Its node must be sub-node of the PMU
  62 +device.
  63 +
  64 +Required properties:
  65 +- compatible: "brcm,bcm53573-ilp"
  66 +- clocks: has to reference an ALP clock
  67 +- #clock-cells: should be <0>
  68 +- clock-output-names: from common clock bindings, should contain clock
  69 +                     name
  70 +
  71 +Example:
  72 +
  73 +pmu@18012000 {
  74 +       compatible = "simple-mfd", "syscon";
  75 +       reg = <0x18012000 0x00001000>;
  76 +
  77 +       ilp {
  78 +               compatible = "brcm,bcm53573-ilp";
  79 +               clocks = <&alp>;
  80 +               #clock-cells = <0>;
  81 +               clock-output-names = "ilp";
  82 +       };
  83 +};
  84 --- a/drivers/clk/bcm/Makefile
  85 +++ b/drivers/clk/bcm/Makefile
  86 @@ -8,3 +8,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC)  += clk-ns
  87  obj-$(CONFIG_ARCH_BCM_CYGNUS)  += clk-cygnus.o
  88  obj-$(CONFIG_ARCH_BCM_NSP)     += clk-nsp.o
  89  obj-$(CONFIG_ARCH_BCM_5301X)   += clk-nsp.o
  90 +obj-$(CONFIG_ARCH_BCM_53573)   += clk-bcm53573-ilp.o
  91 --- /dev/null
  92 +++ b/drivers/clk/bcm/clk-bcm53573-ilp.c
  93 @@ -0,0 +1,148 @@
  94 +/*
  95 + * Copyright (C) 2016 Rafał Miłecki <rafal@milecki.pl>
  96 + *
  97 + * This program is free software; you can redistribute it and/or modify
  98 + * it under the terms of the GNU General Public License version 2 as
  99 + * published by the Free Software Foundation.
 100 + */
 101 +
 102 +#include <linux/clk-provider.h>
 103 +#include <linux/err.h>
 104 +#include <linux/io.h>
 105 +#include <linux/mfd/syscon.h>
 106 +#include <linux/of.h>
 107 +#include <linux/of_address.h>
 108 +#include <linux/regmap.h>
 109 +#include <linux/slab.h>
 110 +
 111 +#define PMU_XTAL_FREQ_RATIO                    0x66c
 112 +#define  XTAL_ALP_PER_4ILP                     0x00001fff
 113 +#define  XTAL_CTL_EN                           0x80000000
 114 +#define PMU_SLOW_CLK_PERIOD                    0x6dc
 115 +
 116 +struct bcm53573_ilp {
 117 +       struct clk_hw hw;
 118 +       struct regmap *regmap;
 119 +};
 120 +
 121 +static int bcm53573_ilp_enable(struct clk_hw *hw)
 122 +{
 123 +       struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 124 +
 125 +       regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0x10199);
 126 +       regmap_write(ilp->regmap, 0x674, 0x10000);
 127 +
 128 +       return 0;
 129 +}
 130 +
 131 +static void bcm53573_ilp_disable(struct clk_hw *hw)
 132 +{
 133 +       struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 134 +
 135 +       regmap_write(ilp->regmap, PMU_SLOW_CLK_PERIOD, 0);
 136 +       regmap_write(ilp->regmap, 0x674, 0);
 137 +}
 138 +
 139 +static unsigned long bcm53573_ilp_recalc_rate(struct clk_hw *hw,
 140 +                                             unsigned long parent_rate)
 141 +{
 142 +       struct bcm53573_ilp *ilp = container_of(hw, struct bcm53573_ilp, hw);
 143 +       struct regmap *regmap = ilp->regmap;
 144 +       u32 last_val, cur_val;
 145 +       int sum = 0, num = 0, loop_num = 0;
 146 +       int avg;
 147 +
 148 +       /* Enable measurement */
 149 +       regmap_write(regmap, PMU_XTAL_FREQ_RATIO, XTAL_CTL_EN);
 150 +
 151 +       /* Read initial value */
 152 +       regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &last_val);
 153 +       last_val &= XTAL_ALP_PER_4ILP;
 154 +
 155 +       /*
 156 +        * At minimum we should loop for a bit to let hardware do the
 157 +        * measurement. This isn't very accurate however, so for a better
 158 +        * precision lets try getting 20 different values for and use average.
 159 +        */
 160 +       while (num < 20) {
 161 +               regmap_read(regmap, PMU_XTAL_FREQ_RATIO, &cur_val);
 162 +               cur_val &= XTAL_ALP_PER_4ILP;
 163 +
 164 +               if (cur_val != last_val) {
 165 +                       /* Got different value, use it */
 166 +                       sum += cur_val;
 167 +                       num++;
 168 +                       loop_num = 0;
 169 +                       last_val = cur_val;
 170 +               } else if (++loop_num > 5000) {
 171 +                       /* Same value over and over, give up */
 172 +                       sum += cur_val;
 173 +                       num++;
 174 +                       break;
 175 +               }
 176 +
 177 +               cpu_relax();
 178 +       }
 179 +
 180 +       /* Disable measurement to save power */
 181 +       regmap_write(regmap, PMU_XTAL_FREQ_RATIO, 0x0);
 182 +
 183 +       avg = sum / num;
 184 +
 185 +       return parent_rate * 4 / avg;
 186 +}
 187 +
 188 +static const struct clk_ops bcm53573_ilp_clk_ops = {
 189 +       .enable = bcm53573_ilp_enable,
 190 +       .disable = bcm53573_ilp_disable,
 191 +       .recalc_rate = bcm53573_ilp_recalc_rate,
 192 +};
 193 +
 194 +static void bcm53573_ilp_init(struct device_node *np)
 195 +{
 196 +       struct bcm53573_ilp *ilp;
 197 +       struct clk_init_data init = { 0 };
 198 +       const char *parent_name;
 199 +       int err;
 200 +
 201 +       ilp = kzalloc(sizeof(*ilp), GFP_KERNEL);
 202 +       if (!ilp)
 203 +               return;
 204 +
 205 +       parent_name = of_clk_get_parent_name(np, 0);
 206 +       if (!parent_name) {
 207 +               err = -ENOENT;
 208 +               goto err_free_ilp;
 209 +       }
 210 +
 211 +       ilp->regmap = syscon_node_to_regmap(of_get_parent(np));
 212 +       if (IS_ERR(ilp->regmap)) {
 213 +               err = PTR_ERR(ilp->regmap);
 214 +               goto err_free_ilp;
 215 +       }
 216 +
 217 +       init.name = np->name;
 218 +       init.ops = &bcm53573_ilp_clk_ops;
 219 +       init.parent_names = &parent_name;
 220 +       init.num_parents = 1;
 221 +
 222 +       ilp->hw.init = &init;
 223 +       err = clk_hw_register(NULL, &ilp->hw);
 224 +       if (err)
 225 +               goto err_free_ilp;
 226 +
 227 +       err = of_clk_add_hw_provider(np, of_clk_hw_simple_get, &ilp->hw);
 228 +       if (err)
 229 +               goto err_clk_hw_unregister;
 230 +
 231 +       return;
 232 +
 233 +err_clk_hw_unregister:
 234 +       clk_hw_unregister(&ilp->hw);
 235 +err_free_ilp:
 236 +       kfree(ilp);
 237 +       pr_err("Failed to init ILP clock: %d\n", err);
 238 +}
 239 +
 240 +/* We need it very early for arch code, before device model gets ready */
 241 +CLK_OF_DECLARE(bcm53573_ilp_clk, "brcm,bcm53573-ilp", bcm53573_ilp_init);