[PATCH v2 4/4] ARM: bcm2835: Switch to using the new clock driver support.

Eric Anholt
2015-09-10T21:58:31Z

This will give us the ability to set the pixel and HDMI state machine
clocks for the VC4 KMS driver, change the CPU frequency, and
potentially gate clocks in the future (once we also write a power
domain driver). It also gives the uart an explicit clock reference,
so that we don't need to change the physical addresses of the old
fixed clk_bcm2835.c clocks for Raspberry Pi 2 port.

Two clocks get their frequencies updated as a result of this. One is
uart's apb_pclk, which was previously accidentally grabbing the fixed
uart0_pclk due to the apb_pclk not having clk_register_clkdev()
called. The uart doesn't seem to do anything with apb_pclk other than
make sure it's on, so that appears safe (also, as far as I can see,
the apb clock is actually the same as the VPU clock). The other is
EMMC, which according to the docs was supposed to be in the 50-100Mhz
range, but it turns out the firmware needed to change to running it at
the 250Mhz core clock speed to avoid a bug in clock domain crossing.

Additionally, anything using BCM2835_CLOCK_VPU will now have a correct
clock rate if the user configures the boot-time core clock speed using
config.txt.

Signed-off-by: Eric Anholt <eric@anholt.net>
---
arch/arm/boot/dts/bcm2835.dtsi | 52 +++++++++++++++++++++++-------------------
1 file changed, 28 insertions(+), 24 deletions(-)

diff --git a/arch/arm/boot/dts/bcm2835.dtsi b/arch/arm/boot/dts/bcm2835.dtsi
index 301c73f..a6a55b7 100644
--- a/arch/arm/boot/dts/bcm2835.dtsi
+++ b/arch/arm/boot/dts/bcm2835.dtsi
@@ -1,4 +1,5 @@
#include <dt-bindings/pinctrl/bcm2835.h>
+#include <dt-bindings/clock/bcm2835.h>
#include "skeleton.dtsi"

/ {
@@ -21,6 +22,10 @@
compatible = "brcm,bcm2835-system-timer";
reg = <0x7e003000 0x1000>;
interrupts = <1 0>, <1 1>, <1 2>, <1 3>;
+ /* This could be a reference to BCM2835_CLOCK_TIMER,
+ * but we don't have the driver using the common clock
+ * support yet.
+ */
clock-frequency = <1000000>;
};

@@ -57,6 +62,17 @@
reg = <0x7e100000 0x28>;
};

+ clocks: cprman@7e101000 {
+ compatible = "brcm,bcm2835-cprman";
+ #clock-cells = <1>;
+ reg = <0x7e101000 0x2000>;
+
+ /* CPRMAN derives everything from the platform's
+ * oscillator.
+ */
+ clocks = <&clk_osc>;
+ };
+
rng@7e104000 {
compatible = "brcm,bcm2835-rng";
reg = <0x7e104000 0x10>;
@@ -96,7 +112,9 @@
compatible = "brcm,bcm2835-pl011", "arm,pl011", "arm,primecell";
reg = <0x7e201000 0x1000>;
interrupts = <2 25>;
- clock-frequency = <3000000>;
+ clocks = <&clocks BCM2835_CLOCK_UART>,
+ <&clocks BCM2835_CLOCK_VPU>;
+ clock-names = "uartclk", "apb_pclk";
arm,primecell-periphid = <0x00241011>;
};

@@ -115,7 +133,7 @@
compatible = "brcm,bcm2835-spi";
reg = <0x7e204000 0x1000>;
interrupts = <2 22>;
- clocks = <&clk_spi>;
+ clocks = <&clocks BCM2835_CLOCK_VPU>;
#address-cells = <1>;
#size-cells = <0>;
status = "disabled";
@@ -125,7 +143,7 @@
compatible = "brcm,bcm2835-i2c";
reg = <0x7e205000 0x1000>;
interrupts = <2 21>;
- clocks = <&clk_i2c>;
+ clocks = <&clocks BCM2835_CLOCK_VPU>;
#address-cells = <1>;
#size-cells = <0>;
status = "disabled";
@@ -135,7 +153,7 @@
compatible = "brcm,bcm2835-sdhci";
reg = <0x7e300000 0x100>;
interrupts = <2 30>;
- clocks = <&clk_mmc>;
+ clocks = <&clocks BCM2835_CLOCK_EMMC>;
status = "disabled";
};

@@ -143,7 +161,7 @@
compatible = "brcm,bcm2835-i2c";
reg = <0x7e804000 0x1000>;
interrupts = <2 21>;
- clocks = <&clk_i2c>;
+ clocks = <&clocks BCM2835_CLOCK_VPU>;
#address-cells = <1>;
#size-cells = <0>;
status = "disabled";
@@ -165,28 +183,14 @@
#address-cells = <1>;
#size-cells = <0>;

- clk_mmc: clock@0 {
- compatible = "fixed-clock";
- reg = <0>;
- #clock-cells = <0>;
- clock-output-names = "mmc";
- clock-frequency = <100000000>;
- };
-
- clk_i2c: clock@1 {
+ /* The oscillator is the root of the clock tree. */
+ clk_osc: clock@3 {
compatible = "fixed-clock";
- reg = <1>;
+ reg = <3>;
#clock-cells = <0>;
- clock-output-names = "i2c";
- clock-frequency = <250000000>;
+ clock-output-names = "osc";
+ clock-frequency = <19200000>;
};

- clk_spi: clock@2 {
- compatible = "fixed-clock";
- reg = <2>;
- #clock-cells = <0>;
- clock-output-names = "spi";
- clock-frequency = <250000000>;
- };
};
};
--
2.1.4