[Xen-devel] [PATCH 2/2] xen: arm: more flexible scheme for specifying early printk device

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

This allows for early-printk to be specified (for existing UARTS at
least) without the need to edit Rules.mk.

The existing shortcuts are retained, but in a much more compact
fashion.

An unused EARLY_PRINTK_BAUD was removed from the zynqmq settings.

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
---
 docs/misc/arm/early-printk.txt |   34 +++++++++---
 xen/arch/arm/Rules.mk          |  114 ++++++++++++++--------------------------
 2 files changed, 65 insertions(+), 83 deletions(-)

diff --git a/docs/misc/arm/early-printk.txt b/docs/misc/arm/early-printk.txt
index 44df35e..7e03955 100644
--- a/docs/misc/arm/early-printk.txt
+++ b/docs/misc/arm/early-printk.txt
@@ -7,8 +7,32 @@ Note that selecting this option will limit Xen to a single 
UART definition.
 Attempting to boot Xen image on a different platform *will not work*, so this
 option should not be enable for Xens that are intended to be portable.
 
-CONFIG_EARLY_PRINTK=mach
-where mach is the name of the machine:
+CONFIG_EARLY_PRINTK=<INC>,<BASE_ADDRESS>,<OTHER_OPTIONS>
+
+<INC> and <BASE_ADDRESS> are mandatory arguments:
+
+  - <INC> is the name of the driver, see xen/arch/arm/arm{32,64}/debug-*.inc
+    (where <INC> corresponds to the wildcarded *).
+  - <BASE_ADDRESS> is the base physical address of the UART to use
+
+<OTHER_OPTIONS> varies depending on <INC>:
+
+  - 8250,<BASE_ADDRESS>,<REG_SHIFT>
+    - <REG_SHIFT> is, optionally, the left-shift to apply to the
+      register offsets within the uart.
+  - pl011,<BASE_ADDRESS>,<BAUD_RATE>
+    - <BAUD_RATE> is, optionally a baud rate which should be used to
+      configure the UART at start of day.
+
+      If <BAUD_RATE> is not given then the code will not try to
+      initialize the UART, so that bootloader or firmware settings can
+     be used for maximum compatibility.
+  - For all other uarts there are no additional options.
+
+As a convenience it is also possible to select from a list of
+predefined configurations using CONFIG_EARLY_PRINTK=mach where mach is
+the name of the machine:
+
   - brcm: printk with 8250 on Broadcom 7445D0 boards with A15 processors.
   - dra7: printk with 8250 on DRA7 platform
   - exynos5250: printk with the second UART
@@ -27,11 +51,7 @@ where mach is the name of the machine:
   - xgene-storm: printk with 820 on Xgene storm platform
   - zynqmp: printk with Cadence UART for Xilinx ZynqMP SoCs
 
-The base address and baud rate is hardcoded in xen/arch/arm/Rules.mk,
+These settings are is hardcoded in xen/arch/arm/Rules.mk,
 see there when adding support for new machines.
-If not explicitly requested with "EARLY_PRINTK_INIT_UART := y" in Rules.mk,
-the code will not try to initialize the UART, so that bootloader or
-firmware settings can be used for maximum compatibility. The baud rate
-parameter is ignored in this case.
 
 By default early printk is disabled.
diff --git a/xen/arch/arm/Rules.mk b/xen/arch/arm/Rules.mk
index af3448b..b45cb69 100644
--- a/xen/arch/arm/Rules.mk
+++ b/xen/arch/arm/Rules.mk
@@ -42,84 +42,46 @@ EARLY_PRINTK := n
 
 ifeq ($(debug),y)
 
-ifeq ($(CONFIG_EARLY_PRINTK), brcm)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0xF040AB00
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), dra7)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x4806A000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), fastmodel)
-EARLY_PRINTK_INC := pl011
+# See docs/misc/arm/early-printk.txt for syntax
+
+EARLY_PRINTK_brcm           := 8250,0xF040AB00,2
+EARLY_PRINTK_dra7           := 8250,0x4806A000,2
+EARLY_PRINTK_fastmodel      := pl011,0x1c090000,115200
+EARLY_PRINTK_exynos5250     := exynos4210,0x12c20000
+EARLY_PRINTK_hip04-d01      := 8250,0xE4007000,2
+EARLY_PRINTK_juno           := pl011,0x7ff80000
+EARLY_PRINTK_lager          := scif,0xe6e60000
+EARLY_PRINTK_midway         := pl011,0xfff36000
+EARLY_PRINTK_omap5432       := 8250,0x48020000,2
+EARLY_PRINTK_seattle        := pl011,0xe1010000
+EARLY_PRINTK_sun6i          := 8250,0x01c28000,2
+EARLY_PRINTK_sun7i          := 8250,0x01c28000,2
+EARLY_PRINTK_thunderx       := pl011,0x87e024000000
+EARLY_PRINTK_vexpress       := pl011,0x1c090000
+EARLY_PRINTK_xgene-mcdivitt := 8250,0x1c021000,2
+EARLY_PRINTK_xgene-storm    := 8250,0x1c020000,2
+EARLY_PRINTK_zynqmp         := cadence,0xff000000
+
+COMMA := ,
+ifneq ($(EARLY_PRINTK_$(CONFIG_EARLY_PRINTK)),)
+EARLY_PRINTK_CFG := $(subst $(COMMA), ,$(EARLY_PRINTK_$(CONFIG_EARLY_PRINTK)))
+else
+EARLY_PRINTK_CFG := $(subst $(COMMA), ,$(CONFIG_EARLY_PRINTK))
+endif
+
+# Extract configuration from string
+EARLY_PRINTK_INC := $(word 1,$(EARLY_PRINTK_CFG))
+EARLY_UART_BASE_ADDRESS := $(word 2,$(EARLY_PRINTK_CFG))
+
+# UART specific options
+ifeq ($(EARLY_PRINTK_INC),8250)
+EARLY_UART_REG_SHIFT := $(word 3,$(EARLY_PRINTK_CFG))
+endif
+ifeq ($(EARLY_PRINTK_INC),pl011)
+ifneq ($(word 3,$(EARLY_PRINTK_CFG)),)
 EARLY_PRINTK_INIT_UART := y
-EARLY_PRINTK_BAUD := 115200
-EARLY_UART_BASE_ADDRESS := 0x1c090000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), exynos5250)
-EARLY_PRINTK_INC := exynos4210
-EARLY_UART_BASE_ADDRESS := 0x12c20000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), hip04-d01)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0xE4007000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), juno)
-EARLY_PRINTK_INC := pl011
-EARLY_UART_BASE_ADDRESS := 0x7ff80000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), lager)
-EARLY_PRINTK_INC := scif
-EARLY_UART_BASE_ADDRESS := 0xe6e60000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), midway)
-EARLY_PRINTK_INC := pl011
-EARLY_UART_BASE_ADDRESS := 0xfff36000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), omap5432)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x48020000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), seattle)
-EARLY_PRINTK_INC := pl011
-EARLY_UART_BASE_ADDRESS := 0xe1010000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), sun6i)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x01c28000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), sun7i)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x01c28000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), thunderx)
-EARLY_PRINTK_INC := pl011
-EARLY_UART_BASE_ADDRESS := 0x87e024000000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), vexpress)
-EARLY_PRINTK_INC := pl011
-EARLY_UART_BASE_ADDRESS := 0x1c090000
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), xgene-mcdivitt)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x1c021000
-EARLY_UART_REG_SHIFT := 2
-endif
-ifeq ($(CONFIG_EARLY_PRINTK), xgene-storm)
-EARLY_PRINTK_INC := 8250
-EARLY_UART_BASE_ADDRESS := 0x1c020000
-EARLY_UART_REG_SHIFT := 2
+EARLY_PRINTK_BAUD := $(word 3,$(EARLY_PRINTK_CFG))
 endif
-ifeq ($(CONFIG_EARLY_PRINTK), zynqmp)
-EARLY_PRINTK_INC := cadence
-EARLY_PRINTK_BAUD := 115200
-EARLY_UART_BASE_ADDRESS := 0xff000000
 endif
 
 ifneq ($(EARLY_PRINTK_INC),)
-- 
1.7.10.4


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