x86: cpu: introduce scu_ipc_raw_command()

This interface will be used to configure properly some pins on
Merrifield that are shared with SCU.

scu_ipc_raw_command() writes SPTR and DPTR registers before sending
a command to SCU.

This code has been ported from Linux work done by Andy Shevchenko.

Signed-off-by: Georgii Staroselskii <georgii.staroselskii@emlid.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/x86/include/asm/scu.h

@@ -6,6 +6,8 @@
 #define _X86_ASM_SCU_IPC_H_
 
 /* IPC defines the following message types */
+#define IPCMSG_INDIRECT_READ	0x02
+#define IPCMSG_INDIRECT_WRITE	0x05
 #define IPCMSG_WARM_RESET	0xf0
 #define IPCMSG_COLD_RESET	0xf1
 #define IPCMSG_SOFT_RESET	0xf2
@@ -23,5 +25,7 @@ struct ipc_ifwi_version {
 /* Issue commands to the SCU with or without data */
 int scu_ipc_simple_command(u32 cmd, u32 sub);
 int scu_ipc_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out, int outlen);
+int scu_ipc_raw_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out,
+			int outlen, u32 dptr, u32 sptr);
 
 #endif	/* _X86_ASM_SCU_IPC_H_ */

arch/x86/lib/scu.c

@@ -101,6 +101,57 @@ static int scu_ipc_cmd(struct ipc_regs *regs, u32 cmd, u32 sub,
 	return err;
 }
 
+/**
+ * scu_ipc_raw_command() - IPC command with data and pointers
+ * @cmd:    IPC command code
+ * @sub:    IPC command sub type
+ * @in:     input data of this IPC command
+ * @inlen:  input data length in dwords
+ * @out:    output data of this IPC command
+ * @outlen: output data length in dwords
+ * @dptr:   data writing to SPTR register
+ * @sptr:   data writing to DPTR register
+ *
+ * Send an IPC command to SCU with input/output data and source/dest pointers.
+ *
+ * Return:  an IPC error code or 0 on success.
+ */
+int scu_ipc_raw_command(u32 cmd, u32 sub, u32 *in, int inlen, u32 *out,
+			int outlen, u32 dptr, u32 sptr)
+{
+	int inbuflen = DIV_ROUND_UP(inlen, 4);
+	struct udevice *dev;
+	struct scu *scu;
+	int ret;
+
+	ret = syscon_get_by_driver_data(X86_SYSCON_SCU, &dev);
+	if (ret)
+		return ret;
+
+	scu = dev_get_priv(dev);
+
+	/* Up to 16 bytes */
+	if (inbuflen > 4)
+		return -EINVAL;
+
+	writel(dptr, &scu->regs->dptr);
+	writel(sptr, &scu->regs->sptr);
+
+	/*
+	 * SRAM controller doesn't support 8-bit writes, it only
+	 * supports 32-bit writes, so we have to copy input data into
+	 * the temporary buffer, and SCU FW will use the inlen to
+	 * determine the actual input data length in the temporary
+	 * buffer.
+	 */
+
+	u32 inbuf[4] = {0};
+
+	memcpy(inbuf, in, inlen);
+
+	return scu_ipc_cmd(scu->regs, cmd, sub, inbuf, inlen, out, outlen);
+}
+
 /**
  * scu_ipc_simple_command() - send a simple command
  * @cmd: command