*/
#include <common.h>
+#include <div64.h>
#include <asm/errno.h>
#include <asm/io.h>
#include <asm/arch/imx-regs.h>
#endif
#define TEMP_AVG_COUNT 5
#define TEMP_WARN_THRESHOLD 5
-#define REG_VALUE_TO_CEL(ratio, raw) ((raw_n40c - raw) * 100 / ratio - 40)
#define __data __attribute__((section(".data")))
static u32 __data thermal_calib;
+#define FACTOR0 10000000
+#define FACTOR1 15976
+#define FACTOR2 4297157
+
+int raw_to_celsius(unsigned int raw, unsigned int raw_25c, unsigned int raw_hot,
+ unsigned int hot_temp)
+{
+ int temperature;
+
+ if (raw_hot != 0 && hot_temp != 0) {
+ unsigned int raw_n40c, ratio;
+
+ ratio = ((raw_25c - raw_hot) * 100) / (hot_temp - 25);
+ raw_n40c = raw_25c + (13 * ratio) / 20;
+ if (raw <= raw_n40c)
+ temperature = (raw_n40c - raw) * 100 / ratio - 40;
+ else
+ temperature = TEMPERATURE_MIN;
+ } else {
+ u64 temp64 = FACTOR0;
+ unsigned int c1, c2;
+ /*
+ * Derived from linear interpolation:
+ * slope = 0.4297157 - (0.0015976 * 25C fuse)
+ * slope = (FACTOR2 - FACTOR1 * n1) / FACTOR0
+ * (Nmeas - n1) / (Tmeas - t1) = slope
+ * We want to reduce this down to the minimum computation necessary
+ * for each temperature read. Also, we want Tmeas in millicelsius
+ * and we don't want to lose precision from integer division. So...
+ * Tmeas = (Nmeas - n1) / slope + t1
+ * milli_Tmeas = 1000 * (Nmeas - n1) / slope + 1000 * t1
+ * milli_Tmeas = -1000 * (n1 - Nmeas) / slope + 1000 * t1
+ * Let constant c1 = (-1000 / slope)
+ * milli_Tmeas = (n1 - Nmeas) * c1 + 1000 * t1
+ * Let constant c2 = n1 *c1 + 1000 * t1
+ * milli_Tmeas = c2 - Nmeas * c1
+ */
+ temp64 *= 1000;
+ do_div(temp64, FACTOR1 * raw_25c - FACTOR2);
+ c1 = temp64;
+ c2 = raw_25c * c1 + 1000 * 25;
+ temperature = (c2 - raw * c1) / 1000;
+ }
+ return temperature;
+}
+
int read_cpu_temperature(void)
{
unsigned int reg, tmp, i;
- unsigned int raw_25c, raw_hot, hot_temp, raw_n40c, ratio;
+ unsigned int raw_25c, raw_hot, hot_temp;
int temperature;
struct anatop_regs *const anatop = (void *)ANATOP_BASE_ADDR;
struct mx6_ocotp_regs *const ocotp_regs = (void *)OCOTP_BASE_ADDR;
raw_hot = (thermal_calib & 0xfff00) >> 8;
hot_temp = thermal_calib & 0xff;
- ratio = ((raw_25c - raw_hot) * 100) / (hot_temp - 25);
- raw_n40c = raw_25c + (13 * ratio) / 20;
-
/* now we only using single measure, every time we measure
* the temperature, we will power on/off the anadig module
*/
writel(BM_ANADIG_ANA_MISC0_REFTOP_SELBIASOFF, &anatop->ana_misc0_set);
/* write measure freq */
- reg = readl(&anatop->tempsense1);
- reg &= ~BM_ANADIG_TEMPSENSE1_MEASURE_FREQ;
- reg |= 327;
- writel(reg, &anatop->tempsense1);
-
+ writel(327, &anatop->tempsense1);
writel(BM_ANADIG_TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_clr);
writel(BM_ANADIG_TEMPSENSE0_FINISHED, &anatop->tempsense0_clr);
writel(BM_ANADIG_TEMPSENSE0_MEASURE_TEMP, &anatop->tempsense0_set);
- tmp = 0;
- /* read five times of temperature values to get average*/
- for (i = 0; i < 5; i++) {
+ /* average the temperature value over multiple readings */
+ for (i = 0; i < TEMP_AVG_COUNT; i++) {
+ static int failed;
+ int limit = 100;
+
while ((readl(&anatop->tempsense0) &
- BM_ANADIG_TEMPSENSE0_FINISHED) == 0)
+ BM_ANADIG_TEMPSENSE0_FINISHED) == 0) {
udelay(10000);
- reg = readl(&anatop->tempsense0);
- tmp += (reg & BM_ANADIG_TEMPSENSE0_TEMP_VALUE) >>
+ if (--limit < 0)
+ break;
+ }
+ if ((readl(&anatop->tempsense0) &
+ BM_ANADIG_TEMPSENSE0_FINISHED) == 0) {
+ if (!failed) {
+ printf("Failed to read temp sensor\n");
+ failed = 1;
+ }
+ return 0;
+ }
+ failed = 0;
+ reg = (readl(&anatop->tempsense0) &
+ BM_ANADIG_TEMPSENSE0_TEMP_VALUE) >>
BP_ANADIG_TEMPSENSE0_TEMP_VALUE;
+ if (i == 0)
+ tmp = reg;
+ else
+ tmp = (tmp * i + reg) / (i + 1);
writel(BM_ANADIG_TEMPSENSE0_FINISHED,
&anatop->tempsense0_clr);
}
- tmp = tmp / 5;
- if (tmp <= raw_n40c)
- temperature = REG_VALUE_TO_CEL(ratio, tmp);
- else
- temperature = TEMPERATURE_MIN;
+ temperature = raw_to_celsius(tmp, raw_25c, raw_hot, hot_temp);
/* power down anatop thermal sensor */
writel(BM_ANADIG_TEMPSENSE0_POWER_DOWN, &anatop->tempsense0_set);