sunxi: Add support for the rsb (Reduced Serial Bus)

sun8i (A23) introduces a new bus for communicating with the pmic, the rsb,
the rsb is also used to communicate with the pmic on the A80, and is
documented in the A80 user manual.

This commit adds support for this based on the rsb driver from the allwinner
u-boot sources.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>

2 files changed, 159 insertions, 0 deletions

diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile
index 1337b60..3e8975a 100644
--- a/arch/arm/cpu/armv7/sunxi/Makefile
+++ b/arch/arm/cpu/armv7/sunxi/Makefile
@@ -15,6 +15,7 @@ obj-y	+= pinmux.o
 obj-$(CONFIG_MACH_SUN6I)	+= prcm.o
 obj-$(CONFIG_MACH_SUN8I)	+= prcm.o
 obj-$(CONFIG_MACH_SUN6I)	+= p2wi.o
+obj-$(CONFIG_MACH_SUN8I)	+= rsb.o
 obj-$(CONFIG_MACH_SUN4I)	+= clock_sun4i.o
 obj-$(CONFIG_MACH_SUN5I)	+= clock_sun4i.o
 obj-$(CONFIG_MACH_SUN6I)	+= clock_sun6i.o
diff --git a/arch/arm/cpu/armv7/sunxi/rsb.c b/arch/arm/cpu/armv7/sunxi/rsb.c
new file mode 100644
index 0000000..b72bb9d
--- /dev/null
+++ b/arch/arm/cpu/armv7/sunxi/rsb.c
@@ -0,0 +1,158 @@
+/*
+ * (C) Copyright 2014 Hans de Goede <hdegoede@redhat.com>
+ *
+ * Based on allwinner u-boot sources rsb code which is:
+ * (C) Copyright 2007-2013
+ * Allwinner Technology Co., Ltd. <www.allwinnertech.com>
+ * lixiang <lixiang@allwinnertech.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <asm/arch/cpu.h>
+#include <asm/arch/gpio.h>
+#include <asm/arch/prcm.h>
+#include <asm/arch/rsb.h>
+
+static void rsb_cfg_io(void)
+{
+	sunxi_gpio_set_cfgpin(SUNXI_GPL(0), SUN8I_GPL0_R_RSB_SCK);
+	sunxi_gpio_set_cfgpin(SUNXI_GPL(1), SUN8I_GPL1_R_RSB_SDA);
+	sunxi_gpio_set_pull(SUNXI_GPL(0), 1);
+	sunxi_gpio_set_pull(SUNXI_GPL(1), 1);
+	sunxi_gpio_set_drv(SUNXI_GPL(0), 2);
+	sunxi_gpio_set_drv(SUNXI_GPL(1), 2);
+}
+
+static void rsb_set_clk(void)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+	u32 div = 0;
+	u32 cd_odly = 0;
+
+	/* Source is Hosc24M, set RSB clk to 3Mhz */
+	div = 24000000 / 3000000 / 2 - 1;
+	cd_odly = div >> 1;
+	if (!cd_odly)
+		cd_odly = 1;
+
+	writel((cd_odly << 8) | div, &rsb->ccr);
+}
+
+void rsb_init(void)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+
+	rsb_cfg_io();
+
+	/* Enable RSB and PIO clk, and de-assert their resets */
+	prcm_apb0_enable(PRCM_APB0_GATE_PIO | PRCM_APB0_GATE_RSB);
+
+	writel(RSB_CTRL_SOFT_RST, &rsb->ctrl);
+	rsb_set_clk();
+}
+
+static int rsb_await_trans(void)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+	unsigned long tmo = timer_get_us() + 1000000;
+	u32 stat;
+	int ret;
+
+	while (1) {
+		stat = readl(&rsb->stat);
+		if (stat & RSB_STAT_LBSY_INT) {
+			ret = -EBUSY;
+			break;
+		}
+		if (stat & RSB_STAT_TERR_INT) {
+			ret = -EIO;
+			break;
+		}
+		if (stat & RSB_STAT_TOVER_INT) {
+			ret = 0;
+			break;
+		}
+		if (timer_get_us() > tmo) {
+			ret = -ETIME;
+			break;
+		}
+	}
+	writel(stat, &rsb->stat); /* Clear status bits */
+
+	return ret;
+}
+
+int rsb_set_device_mode(u32 device_mode_data)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+	unsigned long tmo = timer_get_us() + 1000000;
+
+	writel(RSB_DMCR_DEVICE_MODE_START | device_mode_data, &rsb->dmcr);
+
+	while (readl(&rsb->dmcr) & RSB_DMCR_DEVICE_MODE_START) {
+		if (timer_get_us() > tmo)
+			return -ETIME;
+	}
+
+	return rsb_await_trans();
+}
+
+static int rsb_do_trans(void)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+
+	setbits_le32(&rsb->ctrl, RSB_CTRL_START_TRANS);
+	return rsb_await_trans();
+}
+
+int rsb_set_device_address(u16 device_addr, u16 runtime_addr)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+
+	writel(RSB_DEVADDR_RUNTIME_ADDR(runtime_addr) |
+	       RSB_DEVADDR_DEVICE_ADDR(device_addr), &rsb->devaddr);
+	writel(RSB_CMD_SET_RTSADDR, &rsb->cmd);
+
+	return rsb_do_trans();
+}
+
+int rsb_write(const u16 runtime_device_addr, const u8 reg_addr, u8 data)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+
+	writel(RSB_DEVADDR_RUNTIME_ADDR(runtime_device_addr), &rsb->devaddr);
+	writel(reg_addr, &rsb->addr);
+	writel(data, &rsb->data);
+	writel(RSB_CMD_BYTE_WRITE, &rsb->cmd);
+
+	return rsb_do_trans();
+}
+
+int rsb_read(const u16 runtime_device_addr, const u8 reg_addr, u8 *data)
+{
+	struct sunxi_rsb_reg * const rsb =
+		(struct sunxi_rsb_reg *)SUNXI_RSB_BASE;
+	int ret;
+
+	writel(RSB_DEVADDR_RUNTIME_ADDR(runtime_device_addr), &rsb->devaddr);
+	writel(reg_addr, &rsb->addr);
+	writel(RSB_CMD_BYTE_READ, &rsb->cmd);
+
+	ret = rsb_do_trans();
+	if (ret)
+		return ret;
+
+	*data = readl(&rsb->data) & 0xff;
+
+	return 0;
+}