Re: [PATCH 1/6] ARM: cygnus: Initial support for Broadcom Cygnus SoC

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Thanks for the review - comments inline.

On 14-10-08 12:54 AM, Arnd Bergmann wrote:
On Tuesday 07 October 2014 22:27:00 Scott Branden wrote:
From: Jonathan Richardson <jonathar@xxxxxxxxxxxx>

Adds initial support for the Cygnus SoC based on Broadcom’s iProc series.

Reviewed-by: Ray Jui <rjui@xxxxxxxxxxxx>
Reviewed-by: Desmond Liu <desmondl@xxxxxxxxxxxx>
Reviewed-by: JD (Jiandong) Zheng <jdzheng@xxxxxxxxxxxx>
Tested-by: Jonathan Richardson <jonathar@xxxxxxxxxxxx>
Signed-off-by: Scott Branden <sbranden@xxxxxxxxxxxx>
---
  arch/arm/mach-bcm/Kconfig      |   31 ++++++++
  arch/arm/mach-bcm/Makefile     |    3 +
  arch/arm/mach-bcm/bcm_cygnus.c |  166 ++++++++++++++++++++++++++++++++++++++++
  3 files changed, 200 insertions(+)
  create mode 100644 arch/arm/mach-bcm/bcm_cygnus.c

diff --git a/arch/arm/mach-bcm/Kconfig b/arch/arm/mach-bcm/Kconfig
index fc93800..2dd3f78 100644
--- a/arch/arm/mach-bcm/Kconfig
+++ b/arch/arm/mach-bcm/Kconfig
@@ -5,6 +5,37 @@ menuconfig ARCH_BCM

  if ARCH_BCM

+config ARCH_BCM_IPROC
+	bool "Broadcom ARMv7 iProc boards" if ARCH_MULTI_V7
+	select ARM_GIC
+	select CACHE_L2X0
+	select HAVE_ARM_TWD if LOCAL_TIMERS
+	select HAVE_CLK
+	select CLKSRC_OF
+	select CLKSRC_MMIO
+	select GENERIC_CLOCKEVENTS
+	select ARM_GLOBAL_TIMER
+	select ARCH_REQUIRE_GPIOLIB
+	select ARM_AMBA
+	select PINCTRL
+	select DEBUG_UART_8250

A lot of these are implied by ARCH_MULTI_V7, just drop them here.

Some others like DEBUG_UART_8250 should remain user-selectable, if
the platform works without them.

Will review. It looks like DEBUG_UART_8250 actually has to move to Kconfig.debug as that is where everyone else selects it.
+	help
+	  This enables support for systems based on Broadcom IPROC architected SoCs.
+	  The IPROC complex contains one or more ARM CPUs along with common
+	  core periperals. Application specific SoCs are created by adding a
+	  uArchitecture containing peripherals outside of the IPROC complex.
+	  Currently supported SoCs are Cygnus.
+
+menu "iProc SoC based Machine types"
+	depends on ARCH_BCM_IPROC
+
+	config ARCH_BCM_CYGNUS
+		bool "Support Broadcom Cygnus board"
+		select USB_ARCH_HAS_EHCI if USB_SUPPORT
+		help
+		  Support for Broadcom Cygnus SoC.
+endmenu

I don't think you need per-board config options. The main option
above should be enough.
This is not a per-board config option. This is actually a per-SoC uArchtecture selection. More major uArchectures will be added to the IPROC. Will Change comment to "Support Broadcom Cygnus SoC"

+
+#define CRMU_MAIL_BOX1      0x03024028
+#define CRMU_SOFT_RESET_CMD 0xFFFFFFFF

Never hardcode physical register locations in source. This should come
from DT, and get moved into a regular 'reset' device driver.

You probably want to use drivers/power/reset/syscon-reboot.c

OK, thanks for advice on where to put reset device driver. Will investigate.
+/* CRU_RESET register */
+static void * __iomem crmu_mail_box1_reg;
+
+#ifdef CONFIG_NEON
+
+#define CRU_BASE                  0x1800e000
+#define CRU_SIZE                  0x34
+#define CRU_CONTROL_OFFSET        0x0
+#define CRU_PWRDWN_EN_OFFSET      0x4
+#define CRU_PWRDWN_STATUS_OFFSET  0x8
+#define CRU_NEON0_HW_RESET  6
+#define CRU_CLAMP_ON_NEON0  20
+#define CRU_PWRONIN_NEON0   21
+#define CRU_PWRONOUT_NEON0  21
+#define CRU_PWROKIN_NEON0   22
+#define CRU_PWROKOUT_NEON0  22
+#define CRU_STATUS_DELAY_NS 500
+#define CRU_MAX_RETRY_COUNT 10
+#define CRU_RETRY_INTVL_US  1
+
+/* Power up the NEON/VFPv3 block. */
+static void bcm_cygnus_powerup_neon(void)
+{
+	void * __iomem cru_base = ioremap(CRU_BASE, CRU_SIZE);
+	u32 reg, i;

Same thing here: this should really use the device node for CRU.

Can you describe what the CRU is? Is this specific to NEON or is
it some general-purpose power management unit?

It's a central resource unit with a lot of random registers to perform various operations. To reduce confusion I'll probably move this out of the kernel init and into the bootloader. This will simplify the kernel init.
+static void __init bcm_cygnus_init(void)
+{
+	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+
+	l2x0_of_init(0, ~0UL);

The l2x0_of_init can be removed now, just move the arguments into the
respective fields of the machine descriptor.

Yes, thanks for pointing this out.
+	crmu_mail_box1_reg = ioremap(CRMU_MAIL_BOX1, SZ_4);
+	WARN_ON(!crmu_mail_box1_reg);
+
+#ifdef CONFIG_NEON
+	bcm_cygnus_powerup_neon();
+#endif
+}

In general, try to avoid #ifdef, use

	if (IS_ENABLED(CONFIG_NEON))
		bcm_cygnus_powerup_neon();

instead.

+
+static const char const *bcm_cygnus_dt_compat[] = {
+	"brcm,cygnus",
+	NULL,
+};
+
+DT_MACHINE_START(BCM_CYGNUS_DT, "Broadcom Cygnus SoC")
+	.init_machine = bcm_cygnus_init,
+	.map_io = debug_ll_io_init,
+	.dt_compat = bcm_cygnus_dt_compat,
+	.restart   = bcm_cygnus_restart
+MACHINE_END

The map_io pointer is unnecessary, and the restart pointer should get
set by the reset driver. I hope we can find a way to avoid the
bcm_cygnus_init callback as well.
bcm_cygnus_init callback can be removed by moving initialization to bootloader.

	Arnd


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