x86: apl: Add PUNIT driver

Add a driver for the Apollo Lake P-unit (power unit). It is modelled as a
syscon driver since it only needs to be probed.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/cpu/apollolake/Makefile

@@ -3,6 +3,9 @@
 # Copyright 2019 Google LLC
 
 obj-$(CONFIG_SPL_BUILD) += systemagent.o
+ifndef CONFIG_TPL_BUILD
+obj-y += punit.o
+endif
 
 obj-y += hostbridge.o
 obj-y += itss.o

arch/x86/cpu/apollolake/punit.c

@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <spl.h>
+#include <asm/cpu.h>
+#include <asm/cpu_common.h>
+#include <asm/intel_regs.h>
+#include <asm/io.h>
+#include <asm/pci.h>
+#include <asm/arch/systemagent.h>
+
+/*
+ * Punit Initialisation code. This all isn't documented, but
+ * this is the recipe.
+ */
+static int punit_init(struct udevice *dev)
+{
+	struct udevice *cpu;
+	u32 reg;
+	ulong start;
+	int ret;
+
+	/* Thermal throttle activation offset */
+	ret = uclass_first_device_err(UCLASS_CPU, &cpu);
+	if (ret)
+		return log_msg_ret("Cannot find CPU", ret);
+	cpu_configure_thermal_target(cpu);
+
+	/*
+	 * Software Core Disable Mask (P_CR_CORE_DISABLE_MASK_0_0_0_MCHBAR).
+	 * Enable all cores here.
+	 */
+	writel(0, MCHBAR_REG(CORE_DISABLE_MASK));
+
+	/* P-Unit bring up */
+	reg = readl(MCHBAR_REG(BIOS_RESET_CPL));
+	if (reg == 0xffffffff) {
+		/* P-unit not found */
+		debug("Punit MMIO not available\n");
+		return -ENOENT;
+	}
+
+	/* Set Punit interrupt pin IPIN offset 3D */
+	dm_pci_write_config8(dev, PCI_INTERRUPT_PIN, 0x2);
+
+	/* Set PUINT IRQ to 24 and INTPIN LOCK */
+	writel(PUINT_THERMAL_DEVICE_IRQ_VEC_NUMBER |
+	       PUINT_THERMAL_DEVICE_IRQ_LOCK,
+	       MCHBAR_REG(PUNIT_THERMAL_DEVICE_IRQ));
+
+	/* Stage0 BIOS Reset Complete (RST_CPL) */
+	enable_bios_reset_cpl();
+
+	/*
+	 * Poll for bit 8 to check if PCODE has completed its action in response
+	 * to BIOS Reset complete.  We wait here till 1 ms for the bit to get
+	 * set.
+	 */
+	start = get_timer(0);
+	while (!(readl(MCHBAR_REG(BIOS_RESET_CPL)) & PCODE_INIT_DONE)) {
+		if (get_timer(start) > 1) {
+			debug("PCODE Init Done timeout\n");
+			return -ETIMEDOUT;
+		}
+		udelay(100);
+	}
+	debug("PUNIT init complete\n");
+
+	return 0;
+}
+
+static int apl_punit_probe(struct udevice *dev)
+{
+	if (spl_phase() == PHASE_SPL)
+		return punit_init(dev);
+
+	return 0;
+}
+
+static const struct udevice_id apl_syscon_ids[] = {
+	{ .compatible = "intel,apl-punit", .data = X86_SYSCON_PUNIT },
+	{ }
+};
+
+U_BOOT_DRIVER(syscon_intel_punit) = {
+	.name		= "intel_punit_syscon",
+	.id		= UCLASS_SYSCON,
+	.of_match	= apl_syscon_ids,
+	.probe		= apl_punit_probe,
+};