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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * Voltage regulators coupler for MediaTek SoCs4 *5 * Copyright (C) 2022 Collabora, Ltd.6 * Author: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>7 */8 9#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt10 11#include <linux/init.h>12#include <linux/kernel.h>13#include <linux/of.h>14#include <linux/regulator/coupler.h>15#include <linux/regulator/driver.h>16#include <linux/regulator/machine.h>17#include <linux/suspend.h>18 19#define to_mediatek_coupler(x) container_of(x, struct mediatek_regulator_coupler, coupler)20 21struct mediatek_regulator_coupler {22 struct regulator_coupler coupler;23 struct regulator_dev *vsram_rdev;24};25 26/*27 * We currently support only couples of not more than two vregs and28 * modify the vsram voltage only when changing voltage of vgpu.29 *30 * This function is limited to the GPU<->SRAM voltages relationships.31 */32static int mediatek_regulator_balance_voltage(struct regulator_coupler *coupler,33 struct regulator_dev *rdev,34 suspend_state_t state)35{36 struct mediatek_regulator_coupler *mrc = to_mediatek_coupler(coupler);37 int max_spread = rdev->constraints->max_spread[0];38 int vsram_min_uV = mrc->vsram_rdev->constraints->min_uV;39 int vsram_max_uV = mrc->vsram_rdev->constraints->max_uV;40 int vsram_target_min_uV, vsram_target_max_uV;41 int min_uV = 0;42 int max_uV = INT_MAX;43 int ret;44 45 /*46 * If the target device is on, setting the SRAM voltage directly47 * is not supported as it scales through its coupled supply voltage.48 *49 * An exception is made in case the use_count is zero: this means50 * that this is the first time we power up the SRAM regulator, which51 * implies that the target device has yet to perform initialization52 * and setting a voltage at that time is harmless.53 */54 if (rdev == mrc->vsram_rdev) {55 if (rdev->use_count == 0)56 return regulator_do_balance_voltage(rdev, state, true);57 58 return -EPERM;59 }60 61 ret = regulator_check_consumers(rdev, &min_uV, &max_uV, state);62 if (ret < 0)63 return ret;64 65 if (min_uV == 0) {66 ret = regulator_get_voltage_rdev(rdev);67 if (ret < 0)68 return ret;69 min_uV = ret;70 }71 72 ret = regulator_check_voltage(rdev, &min_uV, &max_uV);73 if (ret < 0)74 return ret;75 76 /*77 * If we're asked to set a voltage less than VSRAM min_uV, set78 * the minimum allowed voltage on VSRAM, as in this case it is79 * safe to ignore the max_spread parameter.80 */81 vsram_target_min_uV = max(vsram_min_uV, min_uV + max_spread);82 vsram_target_max_uV = min(vsram_max_uV, vsram_target_min_uV + max_spread);83 84 /* Make sure we're not out of range */85 vsram_target_min_uV = min(vsram_target_min_uV, vsram_max_uV);86 87 pr_debug("Setting voltage %d-%duV on %s (minuV %d)\n",88 vsram_target_min_uV, vsram_target_max_uV,89 rdev_get_name(mrc->vsram_rdev), min_uV);90 91 ret = regulator_set_voltage_rdev(mrc->vsram_rdev, vsram_target_min_uV,92 vsram_target_max_uV, state);93 if (ret)94 return ret;95 96 /* The sram voltage is now balanced: update the target vreg voltage */97 return regulator_do_balance_voltage(rdev, state, true);98}99 100static int mediatek_regulator_attach(struct regulator_coupler *coupler,101 struct regulator_dev *rdev)102{103 struct mediatek_regulator_coupler *mrc = to_mediatek_coupler(coupler);104 const char *rdev_name = rdev_get_name(rdev);105 106 /*107 * If we're getting a coupling of more than two regulators here and108 * this means that this is surely not a GPU<->SRAM couple: in that109 * case, we may want to use another coupler implementation, if any,110 * or the generic one: the regulator core will keep walking through111 * the list of couplers when any .attach_regulator() cb returns 1.112 */113 if (rdev->coupling_desc.n_coupled > 2)114 return 1;115 116 if (strstr(rdev_name, "sram")) {117 if (mrc->vsram_rdev)118 return -EINVAL;119 mrc->vsram_rdev = rdev;120 } else if (!strstr(rdev_name, "vgpu") && !strstr(rdev_name, "Vgpu")) {121 return 1;122 }123 124 return 0;125}126 127static int mediatek_regulator_detach(struct regulator_coupler *coupler,128 struct regulator_dev *rdev)129{130 struct mediatek_regulator_coupler *mrc = to_mediatek_coupler(coupler);131 132 if (rdev == mrc->vsram_rdev)133 mrc->vsram_rdev = NULL;134 135 return 0;136}137 138static struct mediatek_regulator_coupler mediatek_coupler = {139 .coupler = {140 .attach_regulator = mediatek_regulator_attach,141 .detach_regulator = mediatek_regulator_detach,142 .balance_voltage = mediatek_regulator_balance_voltage,143 },144};145 146static int mediatek_regulator_coupler_init(void)147{148 if (!of_machine_is_compatible("mediatek,mt8183") &&149 !of_machine_is_compatible("mediatek,mt8186") &&150 !of_machine_is_compatible("mediatek,mt8192"))151 return 0;152 153 return regulator_coupler_register(&mediatek_coupler.coupler);154}155arch_initcall(mediatek_regulator_coupler_init);156 157MODULE_AUTHOR("AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>");158MODULE_DESCRIPTION("MediaTek Regulator Coupler driver");159MODULE_LICENSE("GPL");160