Add device tree binding for the BCM63xx's gated clocks.
The BCM63xx contains clocks gated with a register. Clocks are indexed
by bits in the register and are active high. Clock gate bits are
interleaved with other status bits and configurable clocks in the same
register.
Signed-off-by: Simon Arlott <[email protected]>
---
.../bindings/clock/brcm,bcm63xx-gate-clk.txt | 58 ++++++++++++++++++++++
1 file changed, 58 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
new file mode 100644
index 0000000..3f4ead1
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
@@ -0,0 +1,58 @@
+Broadcom BCM63xx clocks
+
+This binding uses the common clock binding:
+ Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+The BCM63xx contains clocks gated with a register. Clocks are indexed
+by bits in the register and are active high. Clock gate bits are
+interleaved with other status bits and configurable clocks in the same
+register.
+
+Required properties:
+- compatible: Should be "brcm,bcm<soc>-gate-clk", "brcm,bcm63xx-gate-clk"
+- #clock-cells: Should be <1>.
+- regmap: The register map phandle
+- offset: Offset in the register map for the reboot register (in bytes)
+- clocks: The external oscillator clock phandle
+
+Example:
+
+periph_clk: periph_clk {
+ compatible = "brcm,bcm63168-gate-clk", "brcm,bcm63xx-gate-clk";
+ regmap = <&periph_cntl>;
+ offset = <0x4>;
+
+ #clock-cells = <1>;
+ clock-indices =
+ <1>, <2>, <3>, <4>, <5>,
+ <6>, <7>, <8>, <9>, <10>,
+ <11>, <12>, <13>, <14>, <15>,
+ <16>, <17>, <18>, <19>, <20>,
+ <27>, <31>;
+ clock-output-names =
+ "vdsl_qproc", "vdsl_afe", "vdsl", "mips", "wlan_ocp",
+ "dect", "fap0", "fap1", "sar", "robosw",
+ "pcm", "usbd", "usbh", "ipsec", "spi",
+ "hsspi", "pcie", "phymips", "gmac", "nand",
+ "tbus", "robosw250";
+};
+
+timer_clk: timer_clk {
+ compatible = "brcm,bcm63168-gate-clk", "brcm,bcm63xx-gate-clk";
+ regmap = <&timer_cntl>;
+ offset = <0x4>;
+
+ #clock-cells = <1>;
+ clock-indices = <17>, <18>;
+ clock-output-names = "uto_extin", "usb_ref";
+};
+
+ehci0: usb@10002500 {
+ compatible = "brcm,bcm63168-ehci", "brcm,bcm63xx-ehci", "generic-ehci";
+ reg = <0x10002500 0x100>;
+ big-endian;
+ interrupt-parent = <&periph_intc>;
+ interrupts = <10>;
+ clocks = <&periph_clk 13>, <&timer_clk 18>;
+ phys = <&usbh>;
+};
--
2.1.4
--
Simon Arlott
The BCM63xx contains clocks gated with a register. Clocks are indexed
by bits in the register and are active high. Clock gate bits are
interleaved with other status bits and configurable clocks in the same
register.
Enabled by default for BMIPS_GENERIC.
Signed-off-by: Simon Arlott <[email protected]>
---
MAINTAINERS | 1 +
drivers/clk/bcm/Kconfig | 8 ++
drivers/clk/bcm/Makefile | 1 +
drivers/clk/bcm/clk-bcm63xx.c | 187 ++++++++++++++++++++++++++++++++++++++++++
4 files changed, 197 insertions(+)
create mode 100644 drivers/clk/bcm/clk-bcm63xx.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 29e0589..07613dd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2373,6 +2373,7 @@ F: arch/mips/bmips/*
F: arch/mips/include/asm/mach-bmips/*
F: arch/mips/kernel/*bmips*
F: arch/mips/boot/dts/brcm/bcm*.dts*
+F: drivers/clk/bcm/clk-bcm63*
F: drivers/irqchip/irq-bcm63*
F: drivers/irqchip/irq-bcm7*
F: drivers/irqchip/irq-brcmstb*
diff --git a/drivers/clk/bcm/Kconfig b/drivers/clk/bcm/Kconfig
index 85260fb..b9c5464 100644
--- a/drivers/clk/bcm/Kconfig
+++ b/drivers/clk/bcm/Kconfig
@@ -14,3 +14,11 @@ config COMMON_CLK_IPROC
help
Enable common clock framework support for Broadcom SoCs
based on the iProc architecture
+
+config CLK_BCM63XX
+ bool "Broadcom BCM63xx clock support"
+ depends on BMIPS_GENERIC
+ depends on COMMON_CLK
+ default y
+ help
+ Enable clock framework support for Broadcom 63xx SoCs
diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
index 3fc9506..4f5f8ce 100644
--- a/drivers/clk/bcm/Makefile
+++ b/drivers/clk/bcm/Makefile
@@ -8,3 +8,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC) += clk-ns2.o
obj-$(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_CLK_BCM63XX) += clk-bcm63xx.o
diff --git a/drivers/clk/bcm/clk-bcm63xx.c b/drivers/clk/bcm/clk-bcm63xx.c
new file mode 100644
index 0000000..0e8cc06
--- /dev/null
+++ b/drivers/clk/bcm/clk-bcm63xx.c
@@ -0,0 +1,187 @@
+/*
+ * Copyright 2015 Simon Arlott
+ *
+ * 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.
+ *
+ * Based on clk-gate.c:
+ * Copyright (C) 2010-2011 Canonical Ltd <[email protected]>
+ * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <[email protected]>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/regmap.h>
+#include <linux/resource.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+
+/**
+ * DOC: Basic clock which uses a bit in a regmap to gate and ungate the output
+ *
+ * Traits of this clock:
+ * prepare - clk_(un)prepare only ensures parent is (un)prepared
+ * enable - clk_enable and clk_disable are functional & control gating
+ * rate - inherits rate from parent. No clk_set_rate support
+ * parent - fixed parent. No clk_set_parent support
+ */
+
+struct clk_bcm63xx {
+ struct clk_hw hw;
+ struct regmap *map;
+ u32 offset;
+ u32 mask;
+};
+
+#define to_clk_bcm63xx(_hw) container_of(_hw, struct clk_bcm63xx, hw)
+
+static int clk_bcm63xx_enable(struct clk_hw *hw)
+{
+ struct clk_bcm63xx *gate = to_clk_bcm63xx(hw);
+
+ return regmap_write_bits(gate->map, gate->offset,
+ gate->mask, gate->mask);
+}
+
+static void clk_bcm63xx_disable(struct clk_hw *hw)
+{
+ struct clk_bcm63xx *gate = to_clk_bcm63xx(hw);
+
+ regmap_write_bits(gate->map, gate->offset,
+ gate->mask, 0);
+}
+
+static int clk_bcm63xx_is_enabled(struct clk_hw *hw)
+{
+ struct clk_bcm63xx *gate = to_clk_bcm63xx(hw);
+ unsigned int val;
+ int ret;
+
+ ret = regmap_read(gate->map, gate->offset, &val);
+ if (ret)
+ return ret;
+
+ val &= gate->mask;
+
+ return val ? 1 : 0;
+}
+
+const struct clk_ops clk_bcm63xx_ops = {
+ .enable = clk_bcm63xx_enable,
+ .disable = clk_bcm63xx_disable,
+ .is_enabled = clk_bcm63xx_is_enabled,
+};
+
+static struct clk * __init of_bcm63xx_clk_register(const char *parent_name,
+ const char *clk_name, struct regmap *map, u32 offset, u32 mask)
+{
+ struct clk_bcm63xx *gate;
+ struct clk_init_data init;
+ struct clk *ret;
+
+ gate = kzalloc(sizeof(*gate), GFP_KERNEL);
+ if (!gate)
+ return ERR_PTR(-ENOMEM);
+
+ init.name = clk_name;
+ init.ops = &clk_bcm63xx_ops;
+ init.flags = CLK_IS_BASIC;
+ init.parent_names = (parent_name ? &parent_name : NULL);
+ init.num_parents = (parent_name ? 1 : 0);
+ gate->hw.init = &init;
+ gate->map = map;
+ gate->offset = offset;
+ gate->mask = mask;
+
+ ret = clk_register(NULL, &gate->hw);
+ if (IS_ERR(ret))
+ kfree(gate);
+
+ return ret;
+}
+
+static void __init of_bcm63xx_clk_setup(struct device_node *node)
+{
+ struct clk_onecell_data *clk_data;
+ const char *parent_name = NULL;
+ struct regmap *map;
+ u32 offset;
+ unsigned int clocks = 0;
+ int i;
+
+ clk_data = kzalloc(sizeof(*clk_data), GFP_KERNEL);
+ if (!clk_data)
+ return;
+
+ clk_data->clk_num = 32;
+ clk_data->clks = kmalloc_array(clk_data->clk_num,
+ sizeof(*clk_data->clks), GFP_KERNEL);
+
+ for (i = 0; i < clk_data->clk_num; i++)
+ clk_data->clks[i] = ERR_PTR(-ENODEV);
+
+ if (of_clk_get_parent_count(node) > 0)
+ parent_name = of_clk_get_parent_name(node, 0);
+
+ map = syscon_regmap_lookup_by_phandle(node, "regmap");
+ if (IS_ERR(map)) {
+ pr_err("%s: regmap lookup error %ld\n",
+ node->full_name, PTR_ERR(map));
+ goto out;
+ }
+
+ if (of_property_read_u32(node, "offset", &offset)) {
+ pr_err("%s: offset not specified\n", node->full_name);
+ goto out;
+ }
+
+ /* clks[] is sparse, indexed by bit, maximum clocks checked using i */
+ for (i = 0; i < clk_data->clk_num; i++) {
+ u32 bit;
+ const char *clk_name;
+
+ if (of_property_read_u32_index(node, "clock-indices",
+ i, &bit))
+ goto out;
+
+ if (of_property_read_string_index(node, "clock-output-names",
+ i, &clk_name))
+ goto out;
+
+ if (bit >= clk_data->clk_num) {
+ pr_err("%s: clock bit %u out of range\n",
+ node->full_name, bit);
+ continue;
+ }
+
+ if (!IS_ERR(clk_data->clks[bit])) {
+ pr_err("%s: clock bit %u already exists\n",
+ node->full_name, bit);
+ continue;
+ }
+
+ clk_data->clks[bit] = of_bcm63xx_clk_register(parent_name,
+ clk_name, map, offset, BIT(bit));
+ if (!IS_ERR(clk_data->clks[bit]))
+ clocks++;
+ }
+
+out:
+ if (clocks) {
+ of_clk_add_provider(node, of_clk_src_onecell_get, clk_data);
+ pr_info("%s: registered %u clocks\n", node->name, clocks);
+ } else {
+ kfree(clk_data->clks);
+ kfree(clk_data);
+ }
+}
+
+CLK_OF_DECLARE(bcm63xx_clk, "brcm,bcm63xx-gate-clk", of_bcm63xx_clk_setup);
--
2.1.4
--
Simon Arlott
2015-11-30 12:54 GMT-08:00 Simon Arlott <[email protected]>:
> The BCM63xx contains clocks gated with a register. Clocks are indexed
> by bits in the register and are active high. Clock gate bits are
> interleaved with other status bits and configurable clocks in the same
> register.
>
> Enabled by default for BMIPS_GENERIC.
>
> Signed-off-by: Simon Arlott <[email protected]>
> ---
[snip]
> +
> +config CLK_BCM63XX
> + bool "Broadcom BCM63xx clock support"
> + depends on BMIPS_GENERIC
> + depends on COMMON_CLK
> + default y
default BMIPS_GENERIC?
> + help
> + Enable clock framework support for Broadcom 63xx SoCs
> diff --git a/drivers/clk/bcm/Makefile b/drivers/clk/bcm/Makefile
> index 3fc9506..4f5f8ce 100644
> --- a/drivers/clk/bcm/Makefile
> +++ b/drivers/clk/bcm/Makefile
> @@ -8,3 +8,4 @@ obj-$(CONFIG_COMMON_CLK_IPROC) += clk-ns2.o
> 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_CLK_BCM63XX) += clk-bcm63xx.o
> diff --git a/drivers/clk/bcm/clk-bcm63xx.c b/drivers/clk/bcm/clk-bcm63xx.c
> new file mode 100644
> index 0000000..0e8cc06
> --- /dev/null
> +++ b/drivers/clk/bcm/clk-bcm63xx.c
There is a pending clk-bcm63xx.c implementation, covering BCM63138 in
Stephen Boyd's clk/next tree, which you would want to base your
patches on, it is not a huge deal to resolve the conflict, and there
will be separate entry points and functions based on the compatible
string anyway...
> @@ -0,0 +1,187 @@
> +/*
> + * Copyright 2015 Simon Arlott
> + *
> + * 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.
> + *
> + * Based on clk-gate.c:
> + * Copyright (C) 2010-2011 Canonical Ltd <[email protected]>
> + * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <[email protected]>
> + */
I am not really anything very specific to 63xx chips in there, in
fact, this looks like a fairly generic clk-gate driver using regmap to
get its masks and offsets, would it make sense to create
clk-gate-regmap.c which exposes the bulk of what you are doing and you
could match using a specific compatible string?
--
Florian
2015-11-30 12:52 GMT-08:00 Simon Arlott <[email protected]>:
> Add device tree binding for the BCM63xx's gated clocks.
>
> The BCM63xx contains clocks gated with a register. Clocks are indexed
> by bits in the register and are active high. Clock gate bits are
> interleaved with other status bits and configurable clocks in the same
> register.
>
> Signed-off-by: Simon Arlott <[email protected]>
> ---
> .../bindings/clock/brcm,bcm63xx-gate-clk.txt | 58 ++++++++++++++++++++++
> 1 file changed, 58 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
>
> diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
> new file mode 100644
> index 0000000..3f4ead1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
> @@ -0,0 +1,58 @@
> +Broadcom BCM63xx clocks
> +
> +This binding uses the common clock binding:
> + Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +The BCM63xx contains clocks gated with a register. Clocks are indexed
> +by bits in the register and are active high. Clock gate bits are
> +interleaved with other status bits and configurable clocks in the same
> +register.
Most MIPS-based BCM63xx SoCs have clock gating set of registers, these
SoCs are pretty much all of them except 63381 (maybe newer ones too),
this one uses the PMB interface, like 63138 to control resets and
clocks fed to peripherals.
> +
> +Required properties:
> +- compatible: Should be "brcm,bcm<soc>-gate-clk", "brcm,bcm63xx-gate-clk"
I think we would want to start with the lowest common denominator
here, which is either 6345 or 6348.
--
Florian
On Mon, Nov 30, 2015 at 08:52:55PM +0000, Simon Arlott wrote:
> Add device tree binding for the BCM63xx's gated clocks.
>
> The BCM63xx contains clocks gated with a register. Clocks are indexed
> by bits in the register and are active high. Clock gate bits are
> interleaved with other status bits and configurable clocks in the same
> register.
>
> Signed-off-by: Simon Arlott <[email protected]>
> ---
> .../bindings/clock/brcm,bcm63xx-gate-clk.txt | 58 ++++++++++++++++++++++
> 1 file changed, 58 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
>
> diff --git a/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
> new file mode 100644
> index 0000000..3f4ead1
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/brcm,bcm63xx-gate-clk.txt
> @@ -0,0 +1,58 @@
> +Broadcom BCM63xx clocks
> +
> +This binding uses the common clock binding:
> + Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +The BCM63xx contains clocks gated with a register. Clocks are indexed
> +by bits in the register and are active high. Clock gate bits are
> +interleaved with other status bits and configurable clocks in the same
> +register.
> +
> +Required properties:
> +- compatible: Should be "brcm,bcm<soc>-gate-clk", "brcm,bcm63xx-gate-clk"
> +- #clock-cells: Should be <1>.
> +- regmap: The register map phandle
> +- offset: Offset in the register map for the reboot register (in bytes)
> +- clocks: The external oscillator clock phandle
> +
> +Example:
> +
> +periph_clk: periph_clk {
> + compatible = "brcm,bcm63168-gate-clk", "brcm,bcm63xx-gate-clk";
> + regmap = <&periph_cntl>;
What else is in periph_cntrl? Could this all just be part of that node?
Rob
On Fri, December 4, 2015 14:30, Rob Herring wrote:
> On Mon, Nov 30, 2015 at 08:52:55PM +0000, Simon Arlott wrote:
>> +periph_clk: periph_clk {
>> + compatible = "brcm,bcm63168-gate-clk", "brcm,bcm63xx-gate-clk";
>> + regmap = <&periph_cntl>;
>
> What else is in periph_cntrl? Could this all just be part of that node?
uint32 RevID; /* (00) word 0 */
uint32 blkEnables; /* (04) word 1 */ <-- gated clocks
uint32 pll_control; /* (08) word 2 */ <-- system reset controller bit
uint32 deviceTimeoutEn; /* (0c) word 3 */ <-- unknown
uint32 softResetB; /* (10) word 4 */ <-- device reset controller bits
uint32 diagControl; /* (14) word 5 */ <-- unknown
uint32 ExtIrqCfg; /* (18) word 6*/ <-- external interrupt controller
uint32 unused1; /* (1c) word 7 */ <-- (external interrupt controller?)
IrqControl_t IrqControl[3]; /* (20) (40) (60) */ <-- normal interrupt controller
So it has these clocks, two types of reset controller, and the interrupt
controllers, but I've left the interrupt controllers registers out of the
syscon device.
For the registers in the "timer" peripheral at the end of the timer/watchdog
registers:
uint32 EnSwPLL; <-- unknown
uint32 ClkRstCtl;
#define POR_RESET_STATUS (1 << 31) <-- unknown
#define HW_RESET_STATUS (1 << 30) <-- unknown
#define SW_RESET_STATUS (1 << 29) <-- unknown
#define USB_REF_CLKEN (1 << 18) <-- gated clock
#define UTO_EXTIN_CLKEN (1 << 17) <-- gated clock
#define UTO_CLK50_SEL (1 << 16) <-- looks like a clock frequency selection bit
#define FAP2_PLL_CLKEN (1 << 15) <-- gated clock
#define FAP2_PLL_FREQ_SHIFT 12 <-- bits for controlling the frequency
#define FAP1_PLL_CLKEN (1 << 11) <-- gated clock
#define FAP1_PLL_FREQ_SHIFT 8 <-- bits for controlling the frequency
#define WAKEON_DSL (1 << 7) <-- wake on network bit
#define WAKEON_EPHY (1 << 6) <-- wake on network bit
#define DSL_ENERGY_DETECT_ENABLE (1 << 4) <-- energy saving control for network
#define GPHY_1_ENERGY_DETECT_ENABLE (1 << 3) <-- energy saving control for network
#define EPHY_3_ENERGY_DETECT_ENABLE (1 << 2) <-- energy saving control for network
#define EPHY_2_ENERGY_DETECT_ENABLE (1 << 1) <-- energy saving control for network
#define EPHY_1_ENERGY_DETECT_ENABLE (1 << 0) <-- energy saving control for network
I need the usb_ref clock for USB, and I want to be able to disable
uto_extin, fap1 and fap2 as they're unused by anything in the device tree.
The full list of registers is here:
https://github.com/lp0/bcm963xx_4.12L.06B_consumer/blob/master/shared/opensource/include/bcm963xx/63268_map_part.h
--
Simon Arlott
On Fri, December 4, 2015 21:04, Simon Arlott wrote:
> On Fri, December 4, 2015 14:30, Rob Herring wrote:
>> On Mon, Nov 30, 2015 at 08:52:55PM +0000, Simon Arlott wrote:
>>> +periph_clk: periph_clk {
>>> + compatible = "brcm,bcm63168-gate-clk", "brcm,bcm63xx-gate-clk";
>>> + regmap = <&periph_cntl>;
>>
>> What else is in periph_cntrl? Could this all just be part of that node?
>
> uint32 RevID; /* (00) word 0 */
> uint32 blkEnables; /* (04) word 1 */ <-- gated clocks
> uint32 pll_control; /* (08) word 2 */ <-- system reset controller bit
> uint32 deviceTimeoutEn; /* (0c) word 3 */ <-- unknown
> uint32 softResetB; /* (10) word 4 */ <-- device reset controller bits
> uint32 diagControl; /* (14) word 5 */ <-- unknown
> uint32 ExtIrqCfg; /* (18) word 6*/ <-- external interrupt controller
> uint32 unused1; /* (1c) word 7 */ <-- (external interrupt controller?)
> IrqControl_t IrqControl[3]; /* (20) (40) (60) */ <-- normal interrupt controller
On the BCM6368 [1], blkEnables also conatains a power domain bit:
uint32 blkEnables; /* (04) word 1 */
#define USBH_IDDQ_EN (1 << 19)
#define IPSEC_CLK_EN (1 << 18)
#define NAND_CLK_EN (1 << 17)
#define DISABLE_GLESS (1 << 16)
#define USBH_CLK_EN (1 << 15)
#define PCM_CLK_EN (1 << 14)
#define UTOPIA_CLK_EN (1 << 13)
#define ROBOSW_CLK_EN (1 << 12)
#define SAR_CLK_EN (1 << 11)
#define USBD_CLK_EN (1 << 10)
#define SPI_CLK_EN (1 << 9)
#define SWPKT_SAR_CLK_EN (1 << 8)
#define SWPKT_USB_CLK_EN (1 << 7)
#define PHYMIPS_CLK_EN (1 << 6)
#define VDSL_CLK_EN (1 << 5)
#define VDSL_BONDING_EN (1 << 4)
#define VDSL_AFE_EN (1 << 3)
#define VDSL_QPROC_EN (1 << 2)
In order to be able to map these to devices for the BCM63xx SoCs I'm going
to define the power controller binding with "power-domain-indices" and
"power-domain-names" to mirror the clock binding. The separate clk and
generic_pm_domain devices will then handle set/clear of the relevant bits
using the regmap.
[1]
https://code.google.com/p/gfiber-gflt100/source/browse/shared/opensource/include/bcm963xx/6368_map_part.h?r=b292e8c271addbda62104bece90e3c8018714194
--
Simon Arlott