thermal: k3: Add support for bandgap sensors

Add VTM thermal support. In the Voltage Thermal Management
Module(VTM), K3 AM654 supplies a voltage reference and a temperature
sensor feature that are gathered in the band gap voltage and
temperature sensor (VBGAPTS) module. The band gap provides current and
voltage reference for its internal circuits and other analog IP
blocks. The analog-to-digital converter (ADC) produces an output value
that is proportional to the silicon temperature.

Currently reading temperatures only is supported.  There are no
active/passive cooling agent supported.

Signed-off-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Amit Kucheria <amit.kucheria@linaro.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20200407055116.16082-3-j-keerthy@ti.com

1 files changed, 264 insertions, 0 deletions

diff --git a/drivers/thermal/k3_bandgap.c b/drivers/thermal/k3_bandgap.c
new file mode 100644
index 000000000000..35f41e8a0b75
--- /dev/null
+++ b/drivers/thermal/k3_bandgap.c
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * TI Bandgap temperature sensor driver for K3 SoC Family
+ *
+ * Copyright (C) 2020 Texas Instruments Incorporated - http://www.ti.com/
+ */
+
+#include <linux/err.h>
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
+#include <linux/thermal.h>
+#include <linux/types.h>
+
+#define K3_VTM_DEVINFO_PWR0_OFFSET		0x4
+#define K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK	0xf0
+#define K3_VTM_TMPSENS0_CTRL_OFFSET	0x80
+#define K3_VTM_REGS_PER_TS			0x10
+#define K3_VTM_TS_STAT_DTEMP_MASK	0x3ff
+#define K3_VTM_TMPSENS_CTRL_CBIASSEL	BIT(0)
+#define K3_VTM_TMPSENS_CTRL_SOC		BIT(5)
+#define K3_VTM_TMPSENS_CTRL_CLRZ		BIT(6)
+#define K3_VTM_TMPSENS_CTRL_CLKON_REQ	BIT(7)
+
+#define K3_VTM_ADC_BEGIN_VAL		540
+#define K3_VTM_ADC_END_VAL		944
+
+static const int k3_adc_to_temp[] = {
+	-40000, -40000, -40000, -40000, -39800, -39400, -39000, -38600, -38200,
+	-37800, -37400, -37000, -36600, -36200, -35800, -35300, -34700, -34200,
+	-33800, -33400, -33000, -32600, -32200, -31800, -31400, -31000, -30600,
+	-30200, -29800, -29400, -29000, -28600, -28200, -27700, -27100, -26600,
+	-26200, -25800, -25400, -25000, -24600, -24200, -23800, -23400, -23000,
+	-22600, -22200, -21800, -21400, -21000, -20500, -19900, -19400, -19000,
+	-18600, -18200, -17800, -17400, -17000, -16600, -16200, -15800, -15400,
+	-15000, -14600, -14200, -13800, -13400, -13000, -12500, -11900, -11400,
+	-11000, -10600, -10200, -9800, -9400, -9000, -8600, -8200, -7800, -7400,
+	-7000, -6600, -6200, -5800, -5400, -5000, -4500, -3900, -3400, -3000,
+	-2600, -2200, -1800, -1400, -1000, -600, -200, 200, 600, 1000, 1400,
+	1800, 2200, 2600, 3000, 3400, 3900, 4500, 5000, 5400, 5800, 6200, 6600,
+	7000, 7400, 7800, 8200, 8600, 9000, 9400, 9800, 10200, 10600, 11000,
+	11400, 11800, 12200, 12700, 13300, 13800, 14200, 14600, 15000, 15400,
+	15800, 16200, 16600, 17000, 17400, 17800, 18200, 18600, 19000, 19400,
+	19800, 20200, 20600, 21000, 21400, 21900, 22500, 23000, 23400, 23800,
+	24200, 24600, 25000, 25400, 25800, 26200, 26600, 27000, 27400, 27800,
+	28200, 28600, 29000, 29400, 29800, 30200, 30600, 31000, 31400, 31900,
+	32500, 33000, 33400, 33800, 34200, 34600, 35000, 35400, 35800, 36200,
+	36600, 37000, 37400, 37800, 38200, 38600, 39000, 39400, 39800, 40200,
+	40600, 41000, 41400, 41800, 42200, 42600, 43100, 43700, 44200, 44600,
+	45000, 45400, 45800, 46200, 46600, 47000, 47400, 47800, 48200, 48600,
+	49000, 49400, 49800, 50200, 50600, 51000, 51400, 51800, 52200, 52600,
+	53000, 53400, 53800, 54200, 54600, 55000, 55400, 55900, 56500, 57000,
+	57400, 57800, 58200, 58600, 59000, 59400, 59800, 60200, 60600, 61000,
+	61400, 61800, 62200, 62600, 63000, 63400, 63800, 64200, 64600, 65000,
+	65400, 65800, 66200, 66600, 67000, 67400, 67800, 68200, 68600, 69000,
+	69400, 69800, 70200, 70600, 71000, 71500, 72100, 72600, 73000, 73400,
+	73800, 74200, 74600, 75000, 75400, 75800, 76200, 76600, 77000, 77400,
+	77800, 78200, 78600, 79000, 79400, 79800, 80200, 80600, 81000, 81400,
+	81800, 82200, 82600, 83000, 83400, 83800, 84200, 84600, 85000, 85400,
+	85800, 86200, 86600, 87000, 87400, 87800, 88200, 88600, 89000, 89400,
+	89800, 90200, 90600, 91000, 91400, 91800, 92200, 92600, 93000, 93400,
+	93800, 94200, 94600, 95000, 95400, 95800, 96200, 96600, 97000, 97500,
+	98100, 98600, 99000, 99400, 99800, 100200, 100600, 101000, 101400,
+	101800, 102200, 102600, 103000, 103400, 103800, 104200, 104600, 105000,
+	105400, 105800, 106200, 106600, 107000, 107400, 107800, 108200, 108600,
+	109000, 109400, 109800, 110200, 110600, 111000, 111400, 111800, 112200,
+	112600, 113000, 113400, 113800, 114200, 114600, 115000, 115400, 115800,
+	116200, 116600, 117000, 117400, 117800, 118200, 118600, 119000, 119400,
+	119800, 120200, 120600, 121000, 121400, 121800, 122200, 122600, 123000,
+	123400, 123800, 124200, 124600, 124900, 125000,
+};
+
+struct k3_bandgap {
+	void __iomem *base;
+	const struct k3_bandgap_data *conf;
+};
+
+/* common data structures */
+struct k3_thermal_data {
+	struct thermal_zone_device *tzd;
+	struct k3_bandgap *bgp;
+	int sensor_id;
+	u32 ctrl_offset;
+	u32 stat_offset;
+};
+
+static unsigned int vtm_get_best_value(unsigned int s0, unsigned int s1,
+				       unsigned int s2)
+{
+	int d01 = abs(s0 - s1);
+	int d02 = abs(s0 - s2);
+	int d12 = abs(s1 - s2);
+
+	if (d01 <= d02 && d01 <= d12)
+		return (s0 + s1) / 2;
+
+	if (d02 <= d01 && d02 <= d12)
+		return (s0 + s2) / 2;
+
+	return (s1 + s2) / 2;
+}
+
+static int k3_bgp_read_temp(struct k3_thermal_data *devdata,
+			    int *temp)
+{
+	struct k3_bandgap *bgp;
+	unsigned int dtemp, s0, s1, s2;
+
+	bgp = devdata->bgp;
+
+	/*
+	 * Errata is applicable for am654 pg 1.0 silicon. There
+	 * is a variation of the order for 8-10 degree centigrade.
+	 * Work around that by getting the average of two closest
+	 * readings out of three readings everytime we want to
+	 * report temperatures.
+	 *
+	 * Errata workaround.
+	 */
+	s0 = readl(bgp->base + devdata->stat_offset) &
+		K3_VTM_TS_STAT_DTEMP_MASK;
+	s1 = readl(bgp->base + devdata->stat_offset) &
+		K3_VTM_TS_STAT_DTEMP_MASK;
+	s2 = readl(bgp->base + devdata->stat_offset) &
+		K3_VTM_TS_STAT_DTEMP_MASK;
+	dtemp = vtm_get_best_value(s0, s1, s2);
+
+	if (dtemp < K3_VTM_ADC_BEGIN_VAL || dtemp > K3_VTM_ADC_END_VAL)
+		return -EINVAL;
+
+	*temp = k3_adc_to_temp[dtemp - K3_VTM_ADC_BEGIN_VAL];
+
+	return 0;
+}
+
+static int k3_thermal_get_temp(void *devdata, int *temp)
+{
+	struct k3_thermal_data *data = devdata;
+	int ret = 0;
+
+	ret = k3_bgp_read_temp(data, temp);
+	if (ret)
+		return ret;
+
+	return ret;
+}
+
+static const struct thermal_zone_of_device_ops k3_of_thermal_ops = {
+	.get_temp = k3_thermal_get_temp,
+};
+
+static const struct of_device_id of_k3_bandgap_match[];
+
+static int k3_bandgap_probe(struct platform_device *pdev)
+{
+	int ret = 0, cnt, val, id;
+	struct resource *res;
+	struct device *dev = &pdev->dev;
+	struct k3_bandgap *bgp;
+	struct k3_thermal_data *data;
+
+	if (ARRAY_SIZE(k3_adc_to_temp) != (K3_VTM_ADC_END_VAL + 1 -
+						K3_VTM_ADC_BEGIN_VAL))
+		return -EINVAL;
+
+	bgp = devm_kzalloc(&pdev->dev, sizeof(*bgp), GFP_KERNEL);
+	if (!bgp)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	bgp->base = devm_ioremap_resource(dev, res);
+	if (IS_ERR(bgp->base))
+		return PTR_ERR(bgp->base);
+
+	pm_runtime_enable(dev);
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0) {
+		pm_runtime_put_noidle(dev);
+		pm_runtime_disable(dev);
+		return ret;
+	}
+
+	/* Get the sensor count in the VTM */
+	val = readl(bgp->base + K3_VTM_DEVINFO_PWR0_OFFSET);
+	cnt = val & K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK;
+	cnt >>= __ffs(K3_VTM_DEVINFO_PWR0_TEMPSENS_CT_MASK);
+
+	data = devm_kcalloc(dev, cnt, sizeof(*data), GFP_KERNEL);
+	if (!data) {
+		ret = -ENOMEM;
+		goto err_alloc;
+	}
+
+	/* Register the thermal sensors */
+	for (id = 0; id < cnt; id++) {
+		data[id].sensor_id = id;
+		data[id].bgp = bgp;
+		data[id].ctrl_offset = K3_VTM_TMPSENS0_CTRL_OFFSET +
+					id * K3_VTM_REGS_PER_TS;
+		data[id].stat_offset = data[id].ctrl_offset + 0x8;
+
+		val = readl(data[id].bgp->base + data[id].ctrl_offset);
+		val |= (K3_VTM_TMPSENS_CTRL_SOC |
+			K3_VTM_TMPSENS_CTRL_CLRZ |
+			K3_VTM_TMPSENS_CTRL_CLKON_REQ);
+		val &= ~K3_VTM_TMPSENS_CTRL_CBIASSEL;
+		writel(val, data[id].bgp->base + data[id].ctrl_offset);
+
+		data[id].tzd =
+		devm_thermal_zone_of_sensor_register(dev, id,
+						     &data[id],
+						     &k3_of_thermal_ops);
+		if (IS_ERR(data[id].tzd)) {
+			dev_err(dev, "thermal zone device is NULL\n");
+			ret = PTR_ERR(data[id].tzd);
+			goto err_alloc;
+		}
+	}
+
+	platform_set_drvdata(pdev, bgp);
+
+	return 0;
+
+err_alloc:
+	pm_runtime_put_sync(dev);
+	pm_runtime_disable(dev);
+
+	return ret;
+}
+
+static int k3_bandgap_remove(struct platform_device *pdev)
+{
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id of_k3_bandgap_match[] = {
+	{
+		.compatible = "ti,am654-vtm",
+	},
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, of_k3_bandgap_match);
+
+static struct platform_driver k3_bandgap_sensor_driver = {
+	.probe = k3_bandgap_probe,
+	.remove = k3_bandgap_remove,
+	.driver = {
+		.name = "k3-soc-thermal",
+		.of_match_table	= of_k3_bandgap_match,
+	},
+};
+
+module_platform_driver(k3_bandgap_sensor_driver);
+
+MODULE_DESCRIPTION("K3 bandgap temperature sensor driver");
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("J Keerthy <j-keerthy@ti.com>");