misc: k3_avs: add driver for K3 Adaptive Voltage Scaling Class 0

Adaptive Voltage Scaling is a technology used in TI SoCs to optimize
the operating voltage based on characterization data written to efuse
during production. Add a driver to support this feature for K3 line of
SoCs, initially for AM65x.

Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>

3 files changed, 376 insertions, 0 deletions

diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 4985ea033b1..7a8ba587da5 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -421,4 +421,13 @@ config MICROCHIP_FLEXCOM
 	  Only one function can be used at a time and is chosen at boot time
 	  according to the device tree.
 
+config K3_AVS0
+	depends on ARCH_K3 && SPL_DM_REGULATOR
+	bool "AVS class 0 support for K3 devices"
+	help
+	  K3 devices have the optimized voltage values for the main voltage
+	  domains stored in efuse within the VTM IP. This driver reads the
+	  optimized voltage from the efuse, so that it can be programmed
+	  to the PMIC on board.
+
 endmenu
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index f61263640b8..870655e8022 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -66,3 +66,4 @@ obj-$(CONFIG_VEXPRESS_CONFIG) += vexpress_config.o
 obj-$(CONFIG_WINBOND_W83627) += winbond_w83627.o
 obj-$(CONFIG_JZ4780_EFUSE) += jz4780_efuse.o
 obj-$(CONFIG_MICROCHIP_FLEXCOM) += microchip_flexcom.o
+obj-$(CONFIG_K3_AVS0) += k3_avs.o
diff --git a/drivers/misc/k3_avs.c b/drivers/misc/k3_avs.c
new file mode 100644
index 00000000000..dd7fc3d5853
--- /dev/null
+++ b/drivers/misc/k3_avs.c
@@ -0,0 +1,366 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Texas Instruments' K3 Clas 0 Adaptive Voltage Scaling driver
+ *
+ * Copyright (C) 2019 Texas Instruments Incorporated - http://www.ti.com/
+ *      Tero Kristo <t-kristo@ti.com>
+ *
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <asm/io.h>
+#include <i2c.h>
+#include <k3-avs.h>
+#include <power/regulator.h>
+
+#define AM6_VTM_DEVINFO(i)	(priv->base + 0x100 + 0x20 * (i))
+#define AM6_VTM_OPPVID_VD(i)	(priv->base + 0x104 + 0x20 * (i))
+
+#define AM6_VTM_AVS0_SUPPORTED	BIT(12)
+
+#define AM6_VTM_OPP_SHIFT(opp)	(8 * (opp))
+#define AM6_VTM_OPP_MASK	0xff
+
+#define VD_FLAG_INIT_DONE	BIT(0)
+
+struct k3_avs_privdata {
+	void *base;
+	struct vd_config *vd_config;
+};
+
+struct opp {
+	u32 freq;
+	u32 volt;
+};
+
+struct vd_data {
+	int id;
+	u8 opp;
+	u8 flags;
+	int dev_id;
+	int clk_id;
+	struct opp opps[NUM_OPPS];
+	struct udevice *supply;
+};
+
+struct vd_config {
+	struct vd_data *vds;
+	u32 (*efuse_xlate)(struct k3_avs_privdata *priv, int idx, int opp);
+};
+
+static struct k3_avs_privdata *k3_avs_priv;
+
+/**
+ * am6_efuse_voltage: read efuse voltage from VTM
+ * @priv: driver private data
+ * @idx: VD to read efuse for
+ * @opp: opp id to read
+ *
+ * Reads efuse value for the specified OPP, and converts the register
+ * value to a voltage. Returns the voltage in uV, or 0 if nominal voltage
+ * should be used.
+ *
+ * Efuse val to volt conversion logic:
+ *
+ * val > 171 volt increments in 20mV steps with base 171 => 1.66V
+ * val between 115 to 11 increments in 10mV steps with base 115 => 1.1V
+ * val between 15 to 115 increments in 5mV steps with base 15 => .6V
+ * val between 1 to 15 increments in 20mv steps with base 0 => .3V
+ * val 0 is invalid
+ */
+static u32 am6_efuse_xlate(struct k3_avs_privdata *priv, int idx, int opp)
+{
+	u32 val = readl(AM6_VTM_OPPVID_VD(idx));
+
+	val >>= AM6_VTM_OPP_SHIFT(opp);
+	val &= AM6_VTM_OPP_MASK;
+
+	if (!val)
+		return 0;
+
+	if (val > 171)
+		return 1660000 + 20000 * (val - 171);
+
+	if (val > 115)
+		return 1100000 + 10000 * (val - 115);
+
+	if (val > 15)
+		return 600000 + 5000 * (val - 15);
+
+	return 300000 + 20000 * val;
+}
+
+static int k3_avs_program_voltage(struct k3_avs_privdata *priv,
+				  struct vd_data *vd,
+				  int opp_id)
+{
+	u32 volt = vd->opps[opp_id].volt;
+	struct vd_data *vd2;
+
+	if (!vd->supply)
+		return -ENODEV;
+
+	vd->opp = opp_id;
+	vd->flags |= VD_FLAG_INIT_DONE;
+
+	/* Take care of ganged rails and pick the Max amongst them*/
+	for (vd2 = priv->vd_config->vds; vd2->id >= 0; vd2++) {
+		if (vd == vd2)
+			continue;
+
+		if (vd2->supply != vd->supply)
+			continue;
+
+		if (vd2->opps[vd2->opp].volt > volt)
+			volt = vd2->opps[vd2->opp].volt;
+
+		vd2->flags |= VD_FLAG_INIT_DONE;
+	}
+
+	return regulator_set_value(vd->supply, volt);
+}
+
+static struct vd_data *get_vd(struct k3_avs_privdata *priv, int idx)
+{
+	struct vd_data *vd;
+
+	for (vd = priv->vd_config->vds; vd->id >= 0 && vd->id != idx; vd++)
+		;
+
+	if (vd->id < 0)
+		return NULL;
+
+	return vd;
+}
+
+/**
+ * k3_avs_set_opp: Sets the voltage for an arbitrary VD rail
+ * @dev: AVS device
+ * @vdd_id: voltage domain ID
+ * @opp_id: OPP ID
+ *
+ * Programs the desired OPP value for the defined voltage rail. This
+ * should be called from board files if reconfiguration is desired.
+ * Returns 0 on success, negative error value on failure.
+ */
+int k3_avs_set_opp(struct udevice *dev, int vdd_id, int opp_id)
+{
+	struct k3_avs_privdata *priv = dev_get_priv(dev);
+	struct vd_data *vd;
+
+	vd = get_vd(priv, vdd_id);
+	if (!vd)
+		return -EINVAL;
+
+	return k3_avs_program_voltage(priv, vd, opp_id);
+}
+
+static int match_opp(struct vd_data *vd, u32 freq)
+{
+	struct opp *opp;
+	int opp_id;
+
+	for (opp_id = 0; opp_id < NUM_OPPS; opp_id++) {
+		opp = &vd->opps[opp_id];
+		if (opp->freq == freq)
+			return opp_id;
+	}
+
+	printf("No matching OPP found for freq %d.\n", freq);
+
+	return -EINVAL;
+}
+
+/**
+ * k3_avs_notify_freq: Notify clock rate change towards AVS subsystem
+ * @dev_id: Device ID for the clock to be changed
+ * @clk_id: Clock ID for the clock to be changed
+ * @freq: New frequency for clock
+ *
+ * Checks if the provided clock is the MPU clock or not, if not, return
+ * immediately. If MPU clock is provided, maps the provided MPU frequency
+ * towards an MPU OPP, and programs the voltage to the regulator. Return 0
+ * on success, negative error value on failure.
+ */
+int k3_avs_notify_freq(int dev_id, int clk_id, u32 freq)
+{
+	int opp_id;
+	struct k3_avs_privdata *priv = k3_avs_priv;
+	struct vd_data *vd;
+
+	for (vd = priv->vd_config->vds; vd->id >= 0; vd++) {
+		if (vd->dev_id != dev_id || vd->clk_id != clk_id)
+			continue;
+
+		opp_id = match_opp(vd, freq);
+		if (opp_id < 0)
+			return opp_id;
+
+		vd->opp = opp_id;
+		return k3_avs_program_voltage(priv, vd, opp_id);
+	}
+
+	return -EINVAL;
+}
+
+static int k3_avs_configure(struct udevice *dev, struct k3_avs_privdata *priv)
+{
+	struct vd_config *conf;
+	int ret;
+	char pname[20];
+	struct vd_data *vd;
+
+	conf = (void *)dev_get_driver_data(dev);
+
+	priv->vd_config = conf;
+
+	for (vd = conf->vds; vd->id >= 0; vd++) {
+		sprintf(pname, "vdd-supply-%d", vd->id);
+		ret = device_get_supply_regulator(dev, pname, &vd->supply);
+		if (ret)
+			dev_warn(dev, "supply not found for VD%d.\n", vd->id);
+
+		sprintf(pname, "ti,default-opp-%d", vd->id);
+		ret = dev_read_u32_default(dev, pname, -1);
+		if (ret != -1)
+			vd->opp = ret;
+	}
+
+	return 0;
+}
+
+/**
+ * k3_avs_probe: parses VD info from VTM, and re-configures the OPP data
+ *
+ * Parses all VDs on a device calculating the AVS class-0 voltages for them,
+ * and updates the vd_data based on this. The vd_data itself shall be used
+ * to program the required OPPs later on. Returns 0 on success, negative
+ * error value on failure.
+ */
+static int k3_avs_probe(struct udevice *dev)
+{
+	int opp_id;
+	u32 volt;
+	struct opp *opp;
+	struct k3_avs_privdata *priv;
+	struct vd_data *vd;
+	int ret;
+
+	priv = dev_get_priv(dev);
+
+	k3_avs_priv = priv;
+
+	ret = k3_avs_configure(dev, priv);
+	if (ret)
+		return ret;
+
+	priv->base = dev_read_addr_ptr(dev);
+	if (!priv->base)
+		return -ENODEV;
+
+	for (vd = priv->vd_config->vds; vd->id >= 0; vd++) {
+		if (!(readl(AM6_VTM_DEVINFO(vd->id)) &
+		      AM6_VTM_AVS0_SUPPORTED)) {
+			dev_warn(dev, "AVS-class 0 not supported for VD%d\n",
+				 vd->id);
+			continue;
+		}
+
+		for (opp_id = 0; opp_id < NUM_OPPS; opp_id++) {
+			opp = &vd->opps[opp_id];
+
+			if (!opp->freq)
+				continue;
+
+			volt = priv->vd_config->efuse_xlate(priv, vd->id,
+							    opp_id);
+			if (volt)
+				opp->volt = volt;
+		}
+	}
+
+	for (vd = priv->vd_config->vds; vd->id >= 0; vd++) {
+		if (vd->flags & VD_FLAG_INIT_DONE)
+			continue;
+
+		k3_avs_program_voltage(priv, vd, vd->opp);
+	}
+
+	return 0;
+}
+
+static struct vd_data am654_vd_data[] = {
+	{
+		.id = AM6_VDD_CORE,
+		.dev_id = 82, /* AM6_DEV_CBASS0 */
+		.clk_id = 0, /* main sysclk0 */
+		.opp = AM6_OPP_NOM,
+		.opps = {
+			[AM6_OPP_NOM] = {
+				.volt = 1000000,
+				.freq = 250000000, /* CBASS0 */
+			},
+		},
+	},
+	{
+		.id = AM6_VDD_MPU0,
+		.dev_id = 202, /* AM6_DEV_COMPUTE_CLUSTER_A53_0 */
+		.clk_id = 0, /* ARM clock */
+		.opp = AM6_OPP_NOM,
+		.opps = {
+			[AM6_OPP_NOM] = {
+				.volt = 1000000,
+				.freq = 800000000,
+			},
+			[AM6_OPP_OD] = {
+				.volt = 1100000,
+				.freq = 1000000000,
+			},
+			[AM6_OPP_TURBO] = {
+				.volt = 1220000,
+				.freq = 1100000000,
+			},
+		},
+	},
+	{
+		.id = AM6_VDD_MPU1,
+		.opp = AM6_OPP_NOM,
+		.dev_id = 204, /* AM6_DEV_COMPUTE_CLUSTER_A53_2 */
+		.clk_id = 0, /* ARM clock */
+		.opps = {
+			[AM6_OPP_NOM] = {
+				.volt = 1000000,
+				.freq = 800000000,
+			},
+			[AM6_OPP_OD] = {
+				.volt = 1100000,
+				.freq = 1000000000,
+			},
+			[AM6_OPP_TURBO] = {
+				.volt = 1220000,
+				.freq = 1100000000,
+			},
+		},
+	},
+	{ .id = -1 },
+};
+
+static struct vd_config am654_vd_config = {
+	.efuse_xlate = am6_efuse_xlate,
+	.vds = am654_vd_data,
+};
+
+static const struct udevice_id k3_avs_ids[] = {
+	{ .compatible = "ti,am654-avs", .data = (ulong)&am654_vd_config },
+	{}
+};
+
+U_BOOT_DRIVER(k3_avs) = {
+	.name = "k3_avs",
+	.of_match = k3_avs_ids,
+	.id = UCLASS_MISC,
+	.probe = k3_avs_probe,
+	.priv_auto_alloc_size = sizeof(struct k3_avs_privdata),
+};