[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

[David Müller]

The current 83xx FDT implementation adjusts the clock frequency of all
16550 UARTs found in the device tree. This behaviour is ok for the UARTs
which are part of the SoC, but wrong for any additional external UART.

Signed-off-by: David M??ller <d.mueller@elsoft.ch>

---
 arch/powerpc/cpu/mpc83xx/fdt.c |   27 +++++++++++++++++++++++++--
 1 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/cpu/mpc83xx/fdt.c b/arch/powerpc/cpu/mpc83xx/fdt.c
index daf73a6..e13e2b3 100644
--- a/arch/powerpc/cpu/mpc83xx/fdt.c
+++ b/arch/powerpc/cpu/mpc83xx/fdt.c
@@ -50,6 +50,7 @@ void ft_cpu_setup(void *blob, bd_t *bd)
 {
 	immap_t *immr = (immap_t *)CONFIG_SYS_IMMR;
 	int spridr = immr->sysconf.spridr;
+	int off;
 
 	/*
 	 * delete crypto node if not on an E-processor
@@ -131,8 +132,30 @@ void ft_cpu_setup(void *blob, bd_t *bd)
 #endif
 
 #ifdef CONFIG_SYS_NS16550
-	do_fixup_by_compat_u32(blob, "ns16550",
-		"clock-frequency", CONFIG_SYS_NS16550_CLK, 1);
+	/*
+	 * fixup all UART clocks for CPU internal UARTs
+	 * (clock-frequency is usually 0) but do not touch
+	 * any other (external) UARTs
+	 */
+	off = fdt_node_offset_by_compatible(blob, -1, "ns16550");
+
+	while (off != -FDT_ERR_NOTFOUND) {
+		const struct fdt_property *prop;
+		int len;
+
+		prop = fdt_get_property(blob, off, "clock-frequency", &len);
+		if (prop && (len == 4)) {
+			u32 *data = (u32 *)prop->data;
+			u32 val = fdt32_to_cpu(*data);
+			if (val == 0) {
+				val = cpu_to_fdt32(CONFIG_SYS_NS16550_CLK);
+				fdt_setprop(blob, off,
+					    "clock-frequency", &val, 4);
+			}
+		}
+
+		off = fdt_node_offset_by_compatible(blob, off, "ns16550");
+	}
 #endif
 
 	fdt_fixup_memory(blob, (u64)bd->bi_memstart, (u64)bd->bi_memsize);
-- 
1.7.1

[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

[Timur Tabi]

On Fri, Apr 15, 2011 at 7:30 AM, David M?ller <d.mueller@elsoft.ch> wrote:
> The current 83xx FDT implementation adjusts the clock frequency of all
> 16550 UARTs found in the device tree. This behaviour is ok for the UARTs
> which are part of the SoC, but wrong for any additional external UART.

Just out of curiosity -- do you have an example of a device tree with
an external UART?

-- 
Timur Tabi
Linux kernel developer at Freescale

[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

["David Müller (ELSOFT AG)"]

Hello

Timur Tabi wrote:
> Just out of curiosity -- do you have an example of a device tree with
> an external UART?

Yes.

Dave

[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

[Tabi Timur-B04825]

"David M?ller (ELSOFT AG)" wrote:
>> >  Just out of curiosity -- do you have an example of a device tree with
>> >  an external UART?

> Yes.

May I see it?

-- 
Timur Tabi
Linux kernel developer

[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

["David Müller (ELSOFT AG)"]

Tabi Timur-B04825 wrote:
> May I see it?

Please see attached file.

Dave
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[U-Boot] [PATCH] mpc83xx fdt: do not adjust clock frequency of external UARTs

[Kim Phillips]

On Fri, 15 Apr 2011 14:30:33 +0200
David M?ller <d.mueller@elsoft.ch> wrote:

> The current 83xx FDT implementation adjusts the clock frequency of all
> 16550 UARTs found in the device tree. This behaviour is ok for the UARTs
> which are part of the SoC, but wrong for any additional external UART.
> 
> Signed-off-by: David M?ller <d.mueller@elsoft.ch>
> 
> ---
>  arch/powerpc/cpu/mpc83xx/fdt.c |   27 +++++++++++++++++++++++++--
>  1 files changed, 25 insertions(+), 2 deletions(-)

(a) this is not an mpc83xx-specific issue

(b) the fdt code here should instead be modified to only adjust clock
properties on UART nodes contained within the SoC node, not the entire
fdt.

Any UARTs not a part of the SoC should get their clocks updated in
board/ code (or, as in this case, set manually in the device tree).

Kim