[PATCH] ARM: zynq7000: make PS_CLK Kconfigurable

[PATCH] ARM: zynq7000: make PS_CLK Kconfigurable

[Alexander Kurz]

The main clock source on Zynq-7000 based boards (PS_CLK) is not uniform
for all boards, while typical boards are clocked with 33.3MHz, the
Z-7010 based Digilent Zybo board is clocked with 50MHz.
Since barebox is not yet OF aware for Zynq, make PS_CLK board dependent
via Kconfig.

Signed-off-by: Alexander Kurz <akurz@blala.de>
---
 arch/arm/mach-zynq/Kconfig        | 6 ++++++
 arch/arm/mach-zynq/clk-zynq7000.c | 9 ++++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-zynq/Kconfig b/arch/arm/mach-zynq/Kconfig
index d35bd41..ff2aedb 100644
--- a/arch/arm/mach-zynq/Kconfig
+++ b/arch/arm/mach-zynq/Kconfig
@@ -8,6 +8,12 @@ config ZYNQ_DEBUG_LL_UART_BASE
 	hex
 	default 0xe0001000 if MACH_ZEDBOARD
 
+config ZYNQ_PS_CLK
+	int
+	default 33333330 if MACH_ZEDBOARD
+	help
+	  Select the external clock frequency provided to PS_CLK.
+
 choice
 	prompt "Xilinx Zynq type board"
 
diff --git a/arch/arm/mach-zynq/clk-zynq7000.c b/arch/arm/mach-zynq/clk-zynq7000.c
index cd49d84..49e020b 100644
--- a/arch/arm/mach-zynq/clk-zynq7000.c
+++ b/arch/arm/mach-zynq/clk-zynq7000.c
@@ -29,6 +29,13 @@
 #include <mach/zynq7000-regs.h>
 #include <malloc.h>
 
+#ifndef CONFIG_ZYNQ_PS_CLK
+#warning define ZYNQ_PS_CLK for your board
+#define ZYNQ_PS_CLK 33333330
+#else
+#define ZYNQ_PS_CLK CONFIG_ZYNQ_PS_CLK
+#endif
+
 enum zynq_clks {
 	dummy, ps_clk, arm_pll, ddr_pll, io_pll, uart_clk, uart0, uart1,
 	cpu_clk, cpu_6x4x, cpu_3x2x, cpu_2x, cpu_1x,
@@ -361,7 +368,7 @@ static int zynq_clock_probe(struct device_d *dev)
 {
 	struct resource *iores;
 	void __iomem *slcr_base;
-	unsigned long ps_clk_rate = 33333330;
+	unsigned long ps_clk_rate = ZYNQ_PS_CLK;
 
 	iores = dev_request_mem_resource(dev, 0);
 	if (IS_ERR(iores))
-- 
2.1.4


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Re: [PATCH] ARM: zynq7000: make PS_CLK Kconfigurable

[Sascha Hauer]

Hi ALexander,

On Sun, Mar 12, 2017 at 09:27:00PM +0100, Alexander Kurz wrote:
> The main clock source on Zynq-7000 based boards (PS_CLK) is not uniform
> for all boards, while typical boards are clocked with 33.3MHz, the
> Z-7010 based Digilent Zybo board is clocked with 50MHz.
> Since barebox is not yet OF aware for Zynq, make PS_CLK board dependent
> via Kconfig.

We shouldn't encode differences between boards in Kconfig.

One way around it would be to add platform_data to the clk device and
call zynq_init() (with an additional freq argument) from the board code rather
than directly from an initcall.
Creating a small zynq_set_ps_clk() which sets the clock and is to
be called by the board before the clock driver is initialized would be
simpler but also work.

Sascha

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