x86: Add low-power subsystem (lpss) support
This subsystem is present on various Intel SoCs.
Add very basic support for taking an lpss device out of reset.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/arch/x86/cpu/intel_common/lpss.c b/arch/x86/cpu/intel_common/lpss.c
new file mode 100644
index 0000000..26a2d2d
--- /dev/null
+++ b/arch/x86/cpu/intel_common/lpss.c
@@ -0,0 +1,44 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Special driver to handle of-platdata
+ *
+ * Copyright 2019 Google LLC
+ *
+ * Some code from coreboot lpss.c
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <pci.h>
+#include <asm/io.h>
+#include <asm/lpss.h>
+
+enum {
+ LPSS_RESET_CTL_REG = 0x204,
+
+ /*
+ * Bit 1:0 controls LPSS controller reset.
+ *
+ * 00 ->LPSS Host Controller is in reset (Reset Asserted)
+ * 01/10 ->Reserved
+ * 11 ->LPSS Host Controller is NOT at reset (Reset Released)
+ */
+ LPSS_CNT_RST_RELEASE = 3,
+
+ /* Power management control and status register */
+ PME_CTRL_STATUS = 0x84,
+
+ /* Bit 1:0 Powerstate, controls D0 and D3 state */
+ POWER_STATE_MASK = 3,
+};
+
+/* Take controller out of reset */
+void lpss_reset_release(void *regs)
+{
+ writel(LPSS_CNT_RST_RELEASE, regs + LPSS_RESET_CTL_REG);
+}
+
+void lpss_set_power_state(struct udevice *dev, enum lpss_pwr_state state)
+{
+ dm_pci_clrset_config8(dev, PME_CTRL_STATUS, POWER_STATE_MASK, state);
+}