riscv: Add Kendryte K210 SoC support

Add support for the Kendryte K210 RISC-V SoC. For now, this support
only provides a simple sysctl driver allowing to setup the CPU and
uart clock. This support is enabled through the new Kconfig option
SOC_KENDRYTE and defines the config option CONFIG_K210_SYSCTL
to enable the K210 SoC sysctl driver compilation.

The sysctl driver also registers an early SoC initialization function
allowing enabling the general purpose use of the 2MB of SRAM normally
reserved for the SoC AI engine. This initialization function is
automatically called before the dt early initialization using the flat
dt root node compatible property matching the value "kendryte,k210".

Signed-off-by: Christoph Hellwig <[e-mail]>
Signed-off-by: Damien Le Moal <[e-mail]>
[Palmer: Add missing endmenu in Kconfig.socs]
Signed-off-by: Palmer Dabbelt <[e-mail]>

arch/riscv/Kconfig.socs

···
 	help
 	  This enables support for SiFive SoC platform hardware.
 
+config SOC_VIRT
+       bool "QEMU Virt Machine"
+       select VIRTIO_PCI
+       select VIRTIO_BALLOON
+       select VIRTIO_MMIO
+       select VIRTIO_CONSOLE
+       select VIRTIO_NET
+       select NET_9P_VIRTIO
+       select VIRTIO_BLK
+       select SCSI_VIRTIO
+       select DRM_VIRTIO_GPU
+       select HW_RANDOM_VIRTIO
+       select RPMSG_CHAR
+       select RPMSG_VIRTIO
+       select CRYPTO_DEV_VIRTIO
+       select VIRTIO_INPUT
+       select POWER_RESET_SYSCON
+       select POWER_RESET_SYSCON_POWEROFF
+       select GOLDFISH
+       select RTC_DRV_GOLDFISH
+       select SIFIVE_PLIC
+       help
+         This enables support for QEMU Virt Machine.
+
+config SOC_KENDRYTE
+	bool "Kendryte K210 SoC"
+	depends on !MMU
+	help
+	  This enables support for Kendryte K210 SoC platform hardware.
+
 endmenu

drivers/soc/Kconfig

···
 source "drivers/soc/versatile/Kconfig"
 source "drivers/soc/xilinx/Kconfig"
 source "drivers/soc/zte/Kconfig"
+source "drivers/soc/kendryte/Kconfig"
 
 endmenu

drivers/soc/Makefile

···
 obj-$(CONFIG_PLAT_VERSATILE)	+= versatile/
 obj-y				+= xilinx/
 obj-$(CONFIG_ARCH_ZX)		+= zte/
+obj-$(CONFIG_SOC_KENDRYTE)	+= kendryte/

drivers/soc/kendryte/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0
+
+if SOC_KENDRYTE
+
+config K210_SYSCTL
+	bool "Kendryte K210 system controller"
+	default y
+	depends on RISCV
+	help
+	  Enables controlling the K210 various clocks and to enable
+	  general purpose use of the extra 2MB of SRAM normally
+	  reserved for the AI engine.
+
+endif

drivers/soc/kendryte/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_K210_SYSCTL)	+= k210-sysctl.o

drivers/soc/kendryte/k210-sysctl.c

···
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Christoph Hellwig.
+ * Copyright (c) 2019 Western Digital Corporation or its affiliates.
+ */
+#include <linux/types.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/bitfield.h>
+#include <asm/soc.h>
+
+#define K210_SYSCTL_CLK0_FREQ		26000000UL
+
+/* Registers base address */
+#define K210_SYSCTL_SYSCTL_BASE_ADDR	0x50440000ULL
+
+/* Registers */
+#define K210_SYSCTL_PLL0		0x08
+#define K210_SYSCTL_PLL1		0x0c
+/* clkr: 4bits, clkf1: 6bits, clkod: 4bits, bwadj: 4bits */
+#define   PLL_RESET		(1 << 20)
+#define   PLL_PWR		(1 << 21)
+#define   PLL_INTFB		(1 << 22)
+#define   PLL_BYPASS		(1 << 23)
+#define   PLL_TEST		(1 << 24)
+#define   PLL_OUT_EN		(1 << 25)
+#define   PLL_TEST_EN		(1 << 26)
+#define K210_SYSCTL_PLL_LOCK		0x18
+#define   PLL0_LOCK1		(1 << 0)
+#define   PLL0_LOCK2		(1 << 1)
+#define   PLL0_SLIP_CLEAR	(1 << 2)
+#define   PLL0_TEST_CLK_OUT	(1 << 3)
+#define   PLL1_LOCK1		(1 << 8)
+#define   PLL1_LOCK2		(1 << 9)
+#define   PLL1_SLIP_CLEAR	(1 << 10)
+#define   PLL1_TEST_CLK_OUT	(1 << 11)
+#define   PLL2_LOCK1		(1 << 16)
+#define   PLL2_LOCK2		(1 << 16)
+#define   PLL2_SLIP_CLEAR	(1 << 18)
+#define   PLL2_TEST_CLK_OUT	(1 << 19)
+#define K210_SYSCTL_CLKSEL0	0x20
+#define   CLKSEL_ACLK		(1 << 0)
+#define K210_SYSCTL_CLKEN_CENT		0x28
+#define   CLKEN_CPU		(1 << 0)
+#define   CLKEN_SRAM0		(1 << 1)
+#define   CLKEN_SRAM1		(1 << 2)
+#define   CLKEN_APB0		(1 << 3)
+#define   CLKEN_APB1		(1 << 4)
+#define   CLKEN_APB2		(1 << 5)
+#define K210_SYSCTL_CLKEN_PERI		0x2c
+#define   CLKEN_ROM		(1 << 0)
+#define   CLKEN_DMA		(1 << 1)
+#define   CLKEN_AI		(1 << 2)
+#define   CLKEN_DVP		(1 << 3)
+#define   CLKEN_FFT		(1 << 4)
+#define   CLKEN_GPIO		(1 << 5)
+#define   CLKEN_SPI0		(1 << 6)
+#define   CLKEN_SPI1		(1 << 7)
+#define   CLKEN_SPI2		(1 << 8)
+#define   CLKEN_SPI3		(1 << 9)
+#define   CLKEN_I2S0		(1 << 10)
+#define   CLKEN_I2S1		(1 << 11)
+#define   CLKEN_I2S2		(1 << 12)
+#define   CLKEN_I2C0		(1 << 13)
+#define   CLKEN_I2C1		(1 << 14)
+#define   CLKEN_I2C2		(1 << 15)
+#define   CLKEN_UART1		(1 << 16)
+#define   CLKEN_UART2		(1 << 17)
+#define   CLKEN_UART3		(1 << 18)
+#define   CLKEN_AES		(1 << 19)
+#define   CLKEN_FPIO		(1 << 20)
+#define   CLKEN_TIMER0		(1 << 21)
+#define   CLKEN_TIMER1		(1 << 22)
+#define   CLKEN_TIMER2		(1 << 23)
+#define   CLKEN_WDT0		(1 << 24)
+#define   CLKEN_WDT1		(1 << 25)
+#define   CLKEN_SHA		(1 << 26)
+#define   CLKEN_OTP		(1 << 27)
+#define   CLKEN_RTC		(1 << 29)
+
+struct k210_sysctl {
+	void __iomem		*regs;
+	struct clk_hw		hw;
+};
+
+static void k210_set_bits(u32 val, void __iomem *reg)
+{
+	writel(readl(reg) | val, reg);
+}
+
+static void k210_clear_bits(u32 val, void __iomem *reg)
+{
+	writel(readl(reg) & ~val, reg);
+}
+
+static void k210_pll1_enable(void __iomem *regs)
+{
+	u32 val;
+
+	val = readl(regs + K210_SYSCTL_PLL1);
+	val &= ~GENMASK(19, 0);				/* clkr1 = 0 */
+	val |= FIELD_PREP(GENMASK(9, 4), 0x3B);		/* clkf1 = 59 */
+	val |= FIELD_PREP(GENMASK(13, 10), 0x3);	/* clkod1 = 3 */
+	val |= FIELD_PREP(GENMASK(19, 14), 0x3B);	/* bwadj1 = 59 */
+	writel(val, regs + K210_SYSCTL_PLL1);
+
+	k210_clear_bits(PLL_BYPASS, regs + K210_SYSCTL_PLL1);
+	k210_set_bits(PLL_PWR, regs + K210_SYSCTL_PLL1);
+
+	/*
+	 * Reset the pll. The magic NOPs come from the Kendryte reference SDK.
+	 */
+	k210_clear_bits(PLL_RESET, regs + K210_SYSCTL_PLL1);
+	k210_set_bits(PLL_RESET, regs + K210_SYSCTL_PLL1);
+	nop();
+	nop();
+	k210_clear_bits(PLL_RESET, regs + K210_SYSCTL_PLL1);
+
+	for (;;) {
+		val = readl(regs + K210_SYSCTL_PLL_LOCK);
+		if (val & PLL1_LOCK2)
+			break;
+		writel(val | PLL1_SLIP_CLEAR, regs + K210_SYSCTL_PLL_LOCK);
+	}
+
+	k210_set_bits(PLL_OUT_EN, regs + K210_SYSCTL_PLL1);
+}
+
+static unsigned long k210_sysctl_clk_recalc_rate(struct clk_hw *hw,
+		unsigned long parent_rate)
+{
+	struct k210_sysctl *s = container_of(hw, struct k210_sysctl, hw);
+	u32 clksel0, pll0;
+	u64 pll0_freq, clkr0, clkf0, clkod0;
+
+	/*
+	 * If the clock selector is not set, use the base frequency.
+	 * Otherwise, use PLL0 frequency with a frequency divisor.
+	 */
+	clksel0 = readl(s->regs + K210_SYSCTL_CLKSEL0);
+	if (!(clksel0 & CLKSEL_ACLK))
+		return K210_SYSCTL_CLK0_FREQ;
+
+	/*
+	 * Get PLL0 frequency:
+	 * freq = base frequency * clkf0 / (clkr0 * clkod0)
+	 */
+	pll0 = readl(s->regs + K210_SYSCTL_PLL0);
+	clkr0 = 1 + FIELD_GET(GENMASK(3, 0), pll0);
+	clkf0 = 1 + FIELD_GET(GENMASK(9, 4), pll0);
+	clkod0 = 1 + FIELD_GET(GENMASK(13, 10), pll0);
+	pll0_freq = clkf0 * K210_SYSCTL_CLK0_FREQ / (clkr0 * clkod0);
+
+	/* Get the frequency divisor from the clock selector */
+	return pll0_freq / (2ULL << FIELD_GET(0x00000006, clksel0));
+}
+
+static const struct clk_ops k210_sysctl_clk_ops = {
+	.recalc_rate	= k210_sysctl_clk_recalc_rate,
+};
+
+static const struct clk_init_data k210_clk_init_data = {
+	.name		= "k210-sysctl-pll1",
+	.ops		= &k210_sysctl_clk_ops,
+};
+
+static int k210_sysctl_probe(struct platform_device *pdev)
+{
+	struct k210_sysctl *s;
+	int error;
+
+	pr_info("Kendryte K210 SoC sysctl\n");
+
+	s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL);
+	if (!s)
+		return -ENOMEM;
+
+	s->regs = devm_ioremap_resource(&pdev->dev,
+			platform_get_resource(pdev, IORESOURCE_MEM, 0));
+	if (IS_ERR(s->regs))
+		return PTR_ERR(s->regs);
+
+	s->hw.init = &k210_clk_init_data;
+	error = devm_clk_hw_register(&pdev->dev, &s->hw);
+	if (error) {
+		dev_err(&pdev->dev, "failed to register clk");
+		return error;
+	}
+
+	error = devm_of_clk_add_hw_provider(&pdev->dev, of_clk_hw_simple_get,
+					    &s->hw);
+	if (error) {
+		dev_err(&pdev->dev, "adding clk provider failed\n");
+		return error;
+	}
+
+	return 0;
+}
+
+static const struct of_device_id k210_sysctl_of_match[] = {
+	{ .compatible = "kendryte,k210-sysctl", },
+	{}
+};
+
+static struct platform_driver k210_sysctl_driver = {
+	.driver	= {
+		.name		= "k210-sysctl",
+		.of_match_table	= k210_sysctl_of_match,
+	},
+	.probe			= k210_sysctl_probe,
+};
+
+static int __init k210_sysctl_init(void)
+{
+	return platform_driver_register(&k210_sysctl_driver);
+}
+core_initcall(k210_sysctl_init);
+
+/*
+ * This needs to be called very early during initialization, given that
+ * PLL1 needs to be enabled to be able to use all SRAM.
+ */
+static void __init k210_soc_early_init(const void *fdt)
+{
+	void __iomem *regs;
+
+	regs = ioremap(K210_SYSCTL_SYSCTL_BASE_ADDR, 0x1000);
+	if (!regs)
+		panic("K210 sysctl ioremap");
+
+	/* Enable PLL1 to make the KPU SRAM useable */
+	k210_pll1_enable(regs);
+
+	k210_set_bits(PLL_OUT_EN, regs + K210_SYSCTL_PLL0);
+
+	k210_set_bits(CLKEN_CPU | CLKEN_SRAM0 | CLKEN_SRAM1,
+		      regs + K210_SYSCTL_CLKEN_CENT);
+	k210_set_bits(CLKEN_ROM | CLKEN_TIMER0 | CLKEN_RTC,
+		      regs + K210_SYSCTL_CLKEN_PERI);
+
+	k210_set_bits(CLKSEL_ACLK, regs + K210_SYSCTL_CLKSEL0);
+
+	iounmap(regs);
+}
+SOC_EARLY_INIT_DECLARE(generic_k210, "kendryte,k210", k210_soc_early_init);