hw/arm/npcm7xx: add board setup stub for CPU and UART clocks

When booting directly into a kernel, bypassing the boot loader, the CPU and
UART clocks are not set up correctly. This makes the system appear very
slow, and causes the initrd boot test to fail when optimization is off.

The UART clock must run at 24 MHz. The default 25 MHz reference clock
cannot achieve this, so switch to PLL2/2 @ 480 MHz, which works
perfectly with the default /20 divider.

The CPU clock should run at 800 MHz, so switch it to PLL1/2. PLL1 runs
at 800 MHz by default, so we need to double the feedback divider as well
to make it run at 1600 MHz (so PLL1/2 runs at 800 MHz).

We don't bother checking for PLL lock because we know our emulated PLLs
lock instantly.

Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Havard Skinnemoen <hskinnemoen@google.com>
Message-id: 20200911052101.2602693-13-hskinnemoen@google.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

2 files changed, 33 insertions, 0 deletions

diff --git a/hw/arm/npcm7xx.c b/hw/arm/npcm7xx.c
index 7884b2b03d..037f3a26f2 100644
--- a/hw/arm/npcm7xx.c
+++ b/hw/arm/npcm7xx.c
@@ -55,6 +55,13 @@
 #define NPCM7XX_ROM_BA          (0xffff0000)
 #define NPCM7XX_ROM_SZ          (64 * KiB)
 
+/* Clock configuration values to be fixed up when bypassing bootloader */
+
+/* Run PLL1 at 1600 MHz */
+#define NPCM7XX_PLLCON1_FIXUP_VAL   (0x00402101)
+/* Run the CPU from PLL1 and UART from PLL2 */
+#define NPCM7XX_CLKSEL_FIXUP_VAL    (0x004aaba9)
+
 /*
  * Interrupt lines going into the GIC. This does not include internal Cortex-A9
  * interrupts.
@@ -132,6 +139,29 @@ static const struct {
     },
 };
 
+static void npcm7xx_write_board_setup(ARMCPU *cpu,
+                                      const struct arm_boot_info *info)
+{
+    uint32_t board_setup[] = {
+        0xe59f0010,     /* ldr r0, clk_base_addr */
+        0xe59f1010,     /* ldr r1, pllcon1_value */
+        0xe5801010,     /* str r1, [r0, #16] */
+        0xe59f100c,     /* ldr r1, clksel_value */
+        0xe5801004,     /* str r1, [r0, #4] */
+        0xe12fff1e,     /* bx lr */
+        NPCM7XX_CLK_BA,
+        NPCM7XX_PLLCON1_FIXUP_VAL,
+        NPCM7XX_CLKSEL_FIXUP_VAL,
+    };
+    int i;
+
+    for (i = 0; i < ARRAY_SIZE(board_setup); i++) {
+        board_setup[i] = tswap32(board_setup[i]);
+    }
+    rom_add_blob_fixed("board-setup", board_setup, sizeof(board_setup),
+                       info->board_setup_addr);
+}
+
 static void npcm7xx_write_secondary_boot(ARMCPU *cpu,
                                          const struct arm_boot_info *info)
 {
@@ -170,6 +200,8 @@ static struct arm_boot_info npcm7xx_binfo = {
     .gic_cpu_if_addr        = NPCM7XX_GIC_CPU_IF_ADDR,
     .write_secondary_boot   = npcm7xx_write_secondary_boot,
     .board_id               = -1,
+    .board_setup_addr       = NPCM7XX_BOARD_SETUP_ADDR,
+    .write_board_setup      = npcm7xx_write_board_setup,
 };
 
 void npcm7xx_load_kernel(MachineState *machine, NPCM7xxState *soc)
diff --git a/include/hw/arm/npcm7xx.h b/include/hw/arm/npcm7xx.h
index 78d0d78c52..13106af215 100644
--- a/include/hw/arm/npcm7xx.h
+++ b/include/hw/arm/npcm7xx.h
@@ -37,6 +37,7 @@
 #define NPCM7XX_SMP_LOADER_START        (0xffff0000)  /* Boot ROM */
 #define NPCM7XX_SMP_BOOTREG_ADDR        (0xf080013c)  /* GCR.SCRPAD */
 #define NPCM7XX_GIC_CPU_IF_ADDR         (0xf03fe100)  /* GIC within A9 */
+#define NPCM7XX_BOARD_SETUP_ADDR        (0xffff1000)  /* Boot ROM */
 
 typedef struct NPCM7xxMachine {
     MachineState        parent;