Re: [PATCH v5 2/4] thermal: k3: Add support for bandgap sensors

From: J, KEERTHY
Date: Mon Apr 06 2020 - 21:24:31 EST



On 4/7/2020 12:29 AM, Amit Kucheria wrote:
On Tue, Mar 31, 2020 at 1:24 PM Keerthy <j-keerthy@xxxxxx> wrote:

The bandgap 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.

Your cover letter seems to have useful information that belongs in
this commit message IMO.

Okay. I will add that information here as well.

- Keerthy


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

Signed-off-by: Keerthy <j-keerthy@xxxxxx>
---

Changes in v5:

* Removed thermal work function which was unused.
* Removed unused preve_tenmp and a couple more struct variables.
* Removed couple of redundant header function include.

drivers/thermal/Kconfig | 10 ++
drivers/thermal/Makefile | 1 +
drivers/thermal/k3_bandgap.c | 268 +++++++++++++++++++++++++++++++++++
3 files changed, 279 insertions(+)
create mode 100644 drivers/thermal/k3_bandgap.c

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index 5a05db5438d6..1df434527f8d 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -251,6 +251,16 @@ config IMX_THERMAL
cpufreq is used as the cooling device to throttle CPUs when the
passive trip is crossed.

+config K3_THERMAL
+ tristate "Texas Instruments K3 thermal support"
+ depends on ARCH_K3 || COMPILE_TEST
+ help
+ If you say yes here you get thermal support for the Texas Instruments
+ K3 SoC family. The current chip supported is:
+ - AM654
+
+ This includes temperature reading functionality.
+
config MAX77620_THERMAL
tristate "Temperature sensor driver for Maxim MAX77620 PMIC"
depends on MFD_MAX77620
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 9fb88e26fb10..5ad6535139ae 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -28,6 +28,7 @@ thermal_sys-$(CONFIG_CLOCK_THERMAL) += clock_cooling.o
# devfreq cooling
thermal_sys-$(CONFIG_DEVFREQ_THERMAL) += devfreq_cooling.o

+obj-$(CONFIG_K3_THERMAL) += k3_bandgap.o
# platform thermal drivers
obj-y += broadcom/
obj-$(CONFIG_THERMAL_MMIO) += thermal_mmio.o
diff --git a/drivers/thermal/k3_bandgap.c b/drivers/thermal/k3_bandgap.c
new file mode 100644
index 000000000000..1d976af4461a
--- /dev/null
+++ b/drivers/thermal/k3_bandgap.c
@@ -0,0 +1,268 @@
+// 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/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/pm_runtime.h>
+#include <linux/err.h>
+#include <linux/types.h>
+#include <linux/of_platform.h>
+#include <linux/io.h>
+#include <linux/thermal.h>
+#include <linux/of.h>
+
+#define K3_VTM_DEVINFO_PWR0_OFFSET 0x4
+#define K3_VTM_DEVINFO_PWR0_CVD_CT_MASK 0xf
+#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_MAX_NUM_TS 8
+#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 *ti_thermal;
+ 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, reg_cnt = 0;
+ 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].ti_thermal =
+ devm_thermal_zone_of_sensor_register(dev, id,
+ &data[id],
+ &k3_of_thermal_ops);
+ if (IS_ERR(data[id].ti_thermal)) {
+ dev_err(dev, "thermal zone device is NULL\n");
+ ret = PTR_ERR(data[id].ti_thermal);
+ goto err_alloc;
+ }
+
+ reg_cnt++;
+ }
+
+ platform_set_drvdata(pdev, bgp);
+
+ return 0;
+
+err_alloc:
+ pm_runtime_put_sync(&pdev->dev);
+ pm_runtime_disable(&pdev->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@xxxxxx>");
--
2.17.1