[PATCH 4/5] ARM: imx: Add initial support for Freescale LS1021A

-----Original Message-----
From: Mark Rutland [mailto:mark.rutland at arm.com]
Sent: Wednesday, July 02, 2014 7:21 PM
To: Lu Jingchang-B35083
Cc: shawn.guo at linaro.org; linux-arm-kernel at lists.infradead.org;
devicetree at vger.kernel.org; Lu Jingchang-B35083
Subject: Re: [PATCH 4/5] ARM: imx: Add initial support for Freescale
LS1021A

On Wed, Jul 02, 2014 at 10:02:51AM +0100, Jingchang Lu wrote:

quoted

From: Jingchang Lu <redacted>

diff --git a/arch/arm/mach-imx/mach-ls1021a.c

b/arch/arm/mach-imx/mach-ls1021a.c
new file mode 100644
index 0000000..d1a9bb9

--- /dev/null
+++ b/arch/arm/mach-imx/mach-ls1021a.c

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2013-2014 Freescale Semiconductor, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+modify
+ * it under the terms of the GNU General Public License as published
+by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/of_platform.h>
+#include <asm/mach/arch.h>
+
+#include "common.h"
+
+static const struct of_device_id of_ls1021a_match_table[] = {
+	{
+		.compatible =	"simple-bus",
+	},
+	{
+		.compatible     = "fsl,ifc",
+	},
+	{
+		.compatible	= "fsl,fpga-qixis",
+	},
+	{
+		.compatible	= "fsl,qe",
+	},
+	{}
+};

Are any of thse not always-on (or default-on) MMIO busses?

Is there any reason for not giving them their own drivers?

Normally these are always-on. The child nodes are handled by different drivers,
so to make the devices being added by the of system, they are claimed here.
Thanks.

quoted

+
+static void __init ls1021a_init_machine(void) {
+	mxc_arch_reset_init_dt();

This looks to only be used to set up a watchdog timer. Is there any reason
this logic can't be moved to the watchdog timer driver?

quoted

+
+DT_MACHINE_START(LS1021A, "Freescale LS1021A") #ifdef CONFIG_ZONE_DMA
+	.dma_zone_size	= SZ_128M,
+#endif
+	.init_machine   = ls1021a_init_machine,
+	.dt_compat	= ls1021a_dt_compat,
+	.restart	= mxc_restart,

AFAICT, that jsut uses the WDT for restart. Why can't the watchdog driver
register itself as a restart device?

That would bring us close to an empty machine descriptor, and enable reuse
of the WDT and those busses.

Thanks,
Mark.

Yes, we use the watchdog timer for restart, just as i.MX and Vybrid, the WDT as a
common driver it is still work for watchdog. Thanks.