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Date: Tue, 19 Apr 2022 19:23:22 +0200
From: Daniel Lezcano <daniel.lezcano@...aro.org>
To: Keerthy <j-keerthy@...com>, robh+dt@...nel.org,
rui.zhang@...el.com, amitk@...nel.org, kristo@...nel.org
Cc: linux-pm@...r.kernel.org, vigneshr@...com,
devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 4/4] thermal: k3_j72xx_bandgap: Add the bandgap driver
support
Hi Kheerty,
On 12/04/2022 12:14, Keerthy wrote:
[ ... ]
> +/**
> + * struct err_values - structure containing error/reference values
> + * @refs: reference error values for -40C, 30C, 125C & 150C
> + * @errs: Actual error values for -40C, 30C, 125C & 150C read from the efuse
> + */
> +struct err_values {
> + int refs[4];
> + int errs[4];
> +};
> +
> +static void create_table_segments(struct err_values *err_vals, int seg,
> + int *ref_table)
> +{
> + int m = 0, c, num, den, i, err, idx1, idx2, err1, err2, ref1, ref2;
> +
> + if (seg == 0)
> + idx1 = 0;
> + else
> + idx1 = err_vals->refs[seg];
> +
> + idx2 = err_vals->refs[seg + 1];
> + err1 = err_vals->errs[seg];
> + err2 = err_vals->errs[seg + 1];
> + ref1 = err_vals->refs[seg];
> + ref2 = err_vals->refs[seg + 1];
> +
> + /*
> + * Calculate the slope with adc values read from the register
> + * as the y-axis param and err in adc value as x-axis param
> + */
> + num = ref2 - ref1;
> + den = err2 - err1;
> + if (den)
> + m = num / den;
> + c = ref2 - m * err2;
> +
> + /*
> + * Take care of divide by zero error if error values are same
> + * Or when the slope is 0
> + */
> + if (den != 0 && m != 0) {
> + for (i = idx1; i <= idx2; i++) {
> + err = (i - c) / m;
> + if (((i + err1) < 0) || ((i + err1) > 1023))
> + continue;
Should the test being against 'err' not 'err1' ?
> + derived_table[i] = ref_table[i + err];
> + }
> + } else { /* Constant error take care of divide by zero */
> + for (i = idx1; i <= idx2; i++) {
> + if (((i + err1) < 0) || ((i + err1) > 1023))
> + continue;
> + derived_table[i] = ref_table[i + err1];
> + }
> + }
> +}
> +
> +static int prep_lookup_table(struct err_values *err_vals, int *ref_table)
> +{
> + int inc, i, seg;
> +
> + /*
> + * Fill up the lookup table under 3 segments
> + * region -40C to +30C
> + * region +30C to +125C
> + * region +125C to +150C
> + */
> + for (seg = 0; seg < 3; seg++)
> + create_table_segments(err_vals, seg, ref_table);
> +
> + /* Get to the first valid temperature */
> + i = 0;
> + while (!derived_table[i])
> + i++;
> +
> + /*
> + * Get to the last zero index and back fill the temperature for
> + * sake of continuity
> + */
> + if (i) {
> + /* 300 milli celsius steps */
> + while (i--)
> + derived_table[i] = derived_table[i + 1] - 300;
> + /* case 0 */
> + derived_table[i] = derived_table[i + 1] - 300;
> + }
memset ?
> +
> + /*
> + * Fill the last trailing 0s which are unfilled with increments of
> + * 100 milli celsius till 1023 code
> + */
> + i = 1023;
> + while (!derived_table[i])
> + i--;
All those loop can be replaced by addresses variant IMO. Up to you if
you want to use mem* variants.
eg. void *flz = memrchr(derived_table, 0, size); /* find last zero */
> +
> + i++;
> + inc = 1;
> + while (i < 1024) {
> + derived_table[i] = derived_table[i - 1] + inc * 100;
> + i++;
> + }
> +
> + return 0;
> +}
Please replace all the 1024-ish literals everywhere by a macro
> +struct k3_thermal_data;
> +
> +struct k3_j72xx_bandgap {
> + struct device *dev;
> + void __iomem *base;
> + void __iomem *cfg2_base;
> + void __iomem *fuse_base;
> + struct k3_thermal_data *ts_data[K3_VTM_MAX_NUM_TS];
> +};
> +
> +/* common data structures */
> +struct k3_thermal_data {
> + struct k3_j72xx_bandgap *bgp;
> + u32 ctrl_offset;
> + u32 stat_offset;
> +};
> +
> +static int two_cmp(int tmp, int mask)
> +{
> + tmp = ~(tmp);
> + tmp &= mask;
> + tmp += 1;
> +
> + /* Return negative value */
> + return (0 - tmp);
> +}
> +
> +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 inline int k3_bgp_read_temp(struct k3_thermal_data *devdata,
> + int *temp)
> +{
> + struct k3_j72xx_bandgap *bgp;
> + unsigned int dtemp, s0, s1, s2;
> +
> + bgp = devdata->bgp;
> + /*
> + * Errata is applicable for am654 pg 1.0 silicon/J7ES. There
> + * is a variation of the order for certain degree centigrade on AM654.
> + * 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 < 0 || dtemp > 1023)
> + return -EINVAL;
> +
> + *temp = derived_table[dtemp];
> +
> + return 0;
> +}
> +
> +/* Get temperature callback function for thermal zone */
> +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 int k3_j72xx_bandgap_temp_to_adc_code(int temp)
> +{
> + int low = 0, high = 1023, mid;
> +
> + if (temp > 160000 || temp < -50000)
> + return -EINVAL;
> +
> + /* Binary search to find the adc code */
> + while (low < (high - 1)) {
> + mid = (low + high) / 2;
> + if (temp <= derived_table[mid])
> + high = mid;
> + else
> + low = mid;
> + }
> +
> + return mid;
> +}
> +
> +static void get_efuse_values(int id, struct k3_thermal_data *data, int *err,
> + struct k3_j72xx_bandgap *bgp)
> +{
> + int i, tmp, pow;
> + int ct_offsets[K3_VTM_CORRECTION_TEMP_CNT];
> + int ct_bm[K3_VTM_CORRECTION_TEMP_CNT];
> +
> + /* Populate efuse reg offsets & Bit masks for -40C, 30C, 125C */
> + switch (id) {
> + case 0:
> + ct_offsets[0] = 0x0;
> + ct_offsets[1] = 0x8;
> + ct_offsets[2] = 0x4;
> + ct_bm[0] = 0x3f;
> + ct_bm[1] = 0x1fe000;
> + ct_bm[2] = 0x1ff;
> + break;
> +
> + case 1:
> + ct_offsets[0] = 0x0;
> + ct_offsets[1] = 0x8;
> + ct_offsets[2] = 0x4;
> + ct_bm[0] = 0xfc0;
> + ct_bm[1] = 0x1fe00000;
> + ct_bm[2] = 0x3fe00;
> + break;
> +
> + case 2:
> + ct_offsets[0] = 0x0;
> + ct_offsets[1] = -1;
> + ct_offsets[2] = 0x4;
> + ct_bm[0] = 0x3f000;
> + ct_bm[1] = 0x7f800000;
> + ct_bm[2] = 0x7fc0000;
> + break;
> +
> + case 3:
> + ct_offsets[0] = 0x0;
> + ct_offsets[1] = 0xC;
> + ct_offsets[2] = -1; /* Spread across 2 registers */
> + ct_bm[0] = 0xfc0000;
> + ct_bm[1] = 0x1fe0;
> + ct_bm[2] = 0x1f800000;
> + break;
> +
> + case 4:
> + ct_offsets[0] = 0x0;
> + ct_offsets[1] = 0xc;
> + ct_offsets[2] = 0x8;
> + ct_bm[0] = 0x3f000000;
> + ct_bm[1] = 0x1fe000;
> + ct_bm[2] = 0x1ff0;
> + break;
> + }
The way this is initialized looks strange to me
Why not:
int ct_offsets[][] = {
{ 0x0, 0x8, 0x4 },
{ 0x0, 0x8, 0x4 },
{ 0x0, -1, 0x4 },
{ 0x0, 0xC, -1 }
{ 0x0, 0xc, 0x8 }
};
int ct_bm[][] = {
{ 0x3f, 0x1fe000, 0x1ff },
{ 0xfc0, 0x1fe000, 0x3fe00 },
{ 0x3f000, 0x7f800000, 0x7fc0000 },
{ 0xfc0000, 0x1fe0, 0x1f800000 },
{ 0x3f000000, 0x1fe000, 0x1ff0 }
};
And then : ct_offsets[id][i] below ?
> + for (i = 0; i < 3; i++) {
ARRAY_SIZE on ct_offsets ?
> + /* Extract the offset value using bit-mask */
> + if (ct_offsets[i] == -1 && i == 1) {
> + /* 25C offset Case of Sensor 2 split between 2 regs */
> + tmp = (readl(bgp->fuse_base + 0x8) & 0xE0000000) >> (29);
> + tmp |= ((readl(bgp->fuse_base + 0xC) & 0x1F) << 3);
> + pow = tmp & 0x80;
> + } else if (ct_offsets[i] == -1 && i == 2) {
> + /* 125C Case of Sensor 3 split between 2 regs */
> + tmp = (readl(bgp->fuse_base + 0x4) & 0xF8000000) >> (27);
> + tmp |= ((readl(bgp->fuse_base + 0x8) & 0xF) << 5);
> + pow = tmp & 0x100;
> + } else {
> + tmp = readl(bgp->fuse_base + ct_offsets[i]);
> + tmp &= ct_bm[i];
> + tmp = tmp >> __ffs(ct_bm[i]);
> +
> + /* Obtain the sign bit pow*/
> + pow = ct_bm[i] >> __ffs(ct_bm[i]);
> + pow += 1;
> + pow /= 2;
> + }
> +
> + /* Check for negative value */
> + if (tmp & pow) {
> + /* 2's complement value */
> + tmp = two_cmp(tmp, ct_bm[i] >> __ffs(ct_bm[i]));
> + }
> + err[i] = tmp;
> + }
> +
> + /* Err value for 150C is set to 0 */
> + err[i] = 0;
> +}
> +
> +static void print_look_up_table(struct device *dev, int *ref_table)
> +{
> + int i;
> +
> + dev_dbg(dev, "The contents of derived array\n");
> + dev_dbg(dev, "Code Temperaturei\n");
Typo: "Temperaturei"
> + for (i = 0; i <= 1023; i++)
> + dev_dbg(dev, "%d %d %d\n", i, derived_table[i], ref_table[i]);
> +}
> +
> +static const struct of_device_id of_k3_j72xx_bandgap_match[];
Pointless forward declaration
> +
> +struct k3_j72xx_bandgap_data {
> + unsigned int has_errata_i2128;
> +};
> +
> +static int k3_j72xx_bandgap_probe(struct platform_device *pdev)
> +{
> + int ret = 0, cnt, val, id, table_size = 1024;
table_size to be replaced by the macro mentioned above
> + int high_max, low_temp;
> + struct resource *res;
> + struct device *dev = &pdev->dev;
> + struct k3_j72xx_bandgap *bgp;
> + struct k3_thermal_data *data;
> + int workaround_needed = 0;
> + const struct k3_j72xx_bandgap_data *driver_data;
> + struct thermal_zone_device *ti_thermal;
> + int *ref_table;
> + struct err_values err_vals;
[ ... ]
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