soc: sunxi: Add Allwinner D1 PPU driver

The PPU contains a series of identical MMIO register ranges, one for
each power domain. Each range contains control/status bits for a clock
gate, reset line, output gates, and a power switch. (The clock and reset
are separate from, and in addition to, the bits in the CCU.) It also
contains a hardware power sequence engine to control the other bits.

Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Samuel Holland <samuel@sholland.org>
Link: https://lore.kernel.org/r/20230126063419.15971-3-samuel@sholland.org
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

drivers/soc/sunxi/Kconfig

@@ -19,3 +19,11 @@ config SUNXI_SRAM
 	  Say y here to enable the SRAM controller support. This
 	  device is responsible on mapping the SRAM in the sunXi SoCs
 	  whether to the CPU/DMA, or to the devices.
+
+config SUN20I_PPU
+	bool "Allwinner D1 PPU power domain driver"
+	depends on ARCH_SUNXI || COMPILE_TEST
+	select PM_GENERIC_DOMAINS
+	help
+	  Say y to enable the PPU power domain driver. This saves power
+	  when certain peripherals, such as the video engine, are idle.

drivers/soc/sunxi/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 obj-$(CONFIG_SUNXI_MBUS) +=	sunxi_mbus.o
 obj-$(CONFIG_SUNXI_SRAM) +=	sunxi_sram.o
+obj-$(CONFIG_SUN20I_PPU) +=	sun20i-ppu.o

drivers/soc/sunxi/sun20i-ppu.c

@@ -0,0 +1,207 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/bitfield.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_domain.h>
+#include <linux/reset.h>
+
+#define PD_STATE_ON			1
+#define PD_STATE_OFF			2
+
+#define PD_RSTN_REG			0x00
+#define PD_CLK_GATE_REG			0x04
+#define PD_PWROFF_GATE_REG		0x08
+#define PD_PSW_ON_REG			0x0c
+#define PD_PSW_OFF_REG			0x10
+#define PD_PSW_DELAY_REG		0x14
+#define PD_OFF_DELAY_REG		0x18
+#define PD_ON_DELAY_REG			0x1c
+#define PD_COMMAND_REG			0x20
+#define PD_STATUS_REG			0x24
+#define PD_STATUS_COMPLETE			BIT(1)
+#define PD_STATUS_BUSY				BIT(3)
+#define PD_STATUS_STATE				GENMASK(17, 16)
+#define PD_ACTIVE_CTRL_REG		0x2c
+#define PD_GATE_STATUS_REG		0x30
+#define PD_RSTN_STATUS				BIT(0)
+#define PD_CLK_GATE_STATUS			BIT(1)
+#define PD_PWROFF_GATE_STATUS			BIT(2)
+#define PD_PSW_STATUS_REG		0x34
+
+#define PD_REGS_SIZE			0x80
+
+struct sun20i_ppu_desc {
+	const char *const		*names;
+	unsigned int			num_domains;
+};
+
+struct sun20i_ppu_pd {
+	struct generic_pm_domain	genpd;
+	void __iomem			*base;
+};
+
+#define to_sun20i_ppu_pd(_genpd) \
+	container_of(_genpd, struct sun20i_ppu_pd, genpd)
+
+static bool sun20i_ppu_pd_is_on(const struct sun20i_ppu_pd *pd)
+{
+	u32 status = readl(pd->base + PD_STATUS_REG);
+
+	return FIELD_GET(PD_STATUS_STATE, status) == PD_STATE_ON;
+}
+
+static int sun20i_ppu_pd_set_power(const struct sun20i_ppu_pd *pd, bool power_on)
+{
+	u32 state, status;
+	int ret;
+
+	if (sun20i_ppu_pd_is_on(pd) == power_on)
+		return 0;
+
+	/* Wait for the power controller to be idle. */
+	ret = readl_poll_timeout(pd->base + PD_STATUS_REG, status,
+				 !(status & PD_STATUS_BUSY), 100, 1000);
+	if (ret)
+		return ret;
+
+	state = power_on ? PD_STATE_ON : PD_STATE_OFF;
+	writel(state, pd->base + PD_COMMAND_REG);
+
+	/* Wait for the state transition to complete. */
+	ret = readl_poll_timeout(pd->base + PD_STATUS_REG, status,
+				 FIELD_GET(PD_STATUS_STATE, status) == state &&
+				 (status & PD_STATUS_COMPLETE), 100, 1000);
+	if (ret)
+		return ret;
+
+	/* Clear the completion flag. */
+	writel(status, pd->base + PD_STATUS_REG);
+
+	return 0;
+}
+
+static int sun20i_ppu_pd_power_on(struct generic_pm_domain *genpd)
+{
+	const struct sun20i_ppu_pd *pd = to_sun20i_ppu_pd(genpd);
+
+	return sun20i_ppu_pd_set_power(pd, true);
+}
+
+static int sun20i_ppu_pd_power_off(struct generic_pm_domain *genpd)
+{
+	const struct sun20i_ppu_pd *pd = to_sun20i_ppu_pd(genpd);
+
+	return sun20i_ppu_pd_set_power(pd, false);
+}
+
+static int sun20i_ppu_probe(struct platform_device *pdev)
+{
+	const struct sun20i_ppu_desc *desc;
+	struct device *dev = &pdev->dev;
+	struct genpd_onecell_data *ppu;
+	struct sun20i_ppu_pd *pds;
+	struct reset_control *rst;
+	void __iomem *base;
+	struct clk *clk;
+	int ret;
+
+	desc = of_device_get_match_data(dev);
+	if (!desc)
+		return -EINVAL;
+
+	pds = devm_kcalloc(dev, desc->num_domains, sizeof(*pds), GFP_KERNEL);
+	if (!pds)
+		return -ENOMEM;
+
+	ppu = devm_kzalloc(dev, sizeof(*ppu), GFP_KERNEL);
+	if (!ppu)
+		return -ENOMEM;
+
+	ppu->domains = devm_kcalloc(dev, desc->num_domains,
+				    sizeof(*ppu->domains), GFP_KERNEL);
+	if (!ppu->domains)
+		return -ENOMEM;
+
+	ppu->num_domains = desc->num_domains;
+	platform_set_drvdata(pdev, ppu);
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return PTR_ERR(base);
+
+	clk = devm_clk_get_enabled(dev, NULL);
+	if (IS_ERR(clk))
+		return PTR_ERR(clk);
+
+	rst = devm_reset_control_get_exclusive(dev, NULL);
+	if (IS_ERR(rst))
+		return PTR_ERR(rst);
+
+	ret = reset_control_deassert(rst);
+	if (ret)
+		return ret;
+
+	for (unsigned int i = 0; i < ppu->num_domains; ++i) {
+		struct sun20i_ppu_pd *pd = &pds[i];
+
+		pd->genpd.name		= desc->names[i];
+		pd->genpd.power_off	= sun20i_ppu_pd_power_off;
+		pd->genpd.power_on	= sun20i_ppu_pd_power_on;
+		pd->base		= base + PD_REGS_SIZE * i;
+
+		ret = pm_genpd_init(&pd->genpd, NULL, sun20i_ppu_pd_is_on(pd));
+		if (ret) {
+			dev_warn(dev, "Failed to add '%s' domain: %d\n",
+				 pd->genpd.name, ret);
+			continue;
+		}
+
+		ppu->domains[i] = &pd->genpd;
+	}
+
+	ret = of_genpd_add_provider_onecell(dev->of_node, ppu);
+	if (ret)
+		dev_warn(dev, "Failed to add provider: %d\n", ret);
+
+	return 0;
+}
+
+static const char *const sun20i_d1_ppu_pd_names[] = {
+	"CPU",
+	"VE",
+	"DSP",
+};
+
+static const struct sun20i_ppu_desc sun20i_d1_ppu_desc = {
+	.names		= sun20i_d1_ppu_pd_names,
+	.num_domains	= ARRAY_SIZE(sun20i_d1_ppu_pd_names),
+};
+
+static const struct of_device_id sun20i_ppu_of_match[] = {
+	{
+		.compatible	= "allwinner,sun20i-d1-ppu",
+		.data		= &sun20i_d1_ppu_desc,
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sun20i_ppu_of_match);
+
+static struct platform_driver sun20i_ppu_driver = {
+	.probe	= sun20i_ppu_probe,
+	.driver	= {
+		.name			= "sun20i-ppu",
+		.of_match_table		= sun20i_ppu_of_match,
+		/* Power domains cannot be removed while they are in use. */
+		.suppress_bind_attrs	= true,
+	},
+};
+module_platform_driver(sun20i_ppu_driver);
+
+MODULE_AUTHOR("Samuel Holland <samuel@sholland.org>");
+MODULE_DESCRIPTION("Allwinner D1 PPU power domain driver");
+MODULE_LICENSE("GPL");