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- // SPDX-License-Identifier: GPL-2.0+
- /*
- * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
- * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
- *
- * Originally based on the Linux kernel v4.16 drivers/regulator/stm32-vrefbuf.c
- */
- #define LOG_CATEGORY UCLASS_REGULATOR
- #include <common.h>
- #include <clk.h>
- #include <dm.h>
- #include <asm/io.h>
- #include <dm/device_compat.h>
- #include <linux/bitops.h>
- #include <linux/iopoll.h>
- #include <linux/kernel.h>
- #include <power/regulator.h>
- /* STM32 VREFBUF registers */
- #define STM32_VREFBUF_CSR 0x00
- /* STM32 VREFBUF CSR bitfields */
- #define STM32_VRS GENMASK(6, 4)
- #define STM32_VRS_SHIFT 4
- #define STM32_VRR BIT(3)
- #define STM32_HIZ BIT(1)
- #define STM32_ENVR BIT(0)
- struct stm32_vrefbuf {
- void __iomem *base;
- struct clk clk;
- struct udevice *vdda_supply;
- };
- static const int stm32_vrefbuf_voltages[] = {
- /* Matches resp. VRS = 000b, 001b, 010b, 011b */
- 2500000, 2048000, 1800000, 1500000,
- };
- static int stm32_vrefbuf_set_enable(struct udevice *dev, bool enable)
- {
- struct stm32_vrefbuf *priv = dev_get_priv(dev);
- u32 val;
- int ret;
- if (enable && !(readl(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR)) {
- /*
- * There maybe an overshoot:
- * - when disabling, then re-enabling vrefbuf too quickly
- * - or upon platform reset as external capacitor maybe slow
- * discharging (VREFBUF is HiZ at reset by default).
- * So force active discharge (HiZ=0) for 1ms before enabling.
- */
- clrbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_HIZ);
- udelay(1000);
- }
- clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_ENVR,
- enable ? STM32_ENVR : 0);
- if (!enable)
- return 0;
- /*
- * Vrefbuf startup time depends on external capacitor: wait here for
- * VRR to be set. That means output has reached expected value.
- * ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as
- * arbitrary timeout.
- */
- ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val,
- val & STM32_VRR, 10000);
- if (ret < 0) {
- dev_err(dev, "stm32 vrefbuf timed out: %d\n", ret);
- clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_ENVR,
- STM32_HIZ);
- return ret;
- }
- return 0;
- }
- static int stm32_vrefbuf_get_enable(struct udevice *dev)
- {
- struct stm32_vrefbuf *priv = dev_get_priv(dev);
- return readl(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR;
- }
- static int stm32_vrefbuf_set_value(struct udevice *dev, int uV)
- {
- struct stm32_vrefbuf *priv = dev_get_priv(dev);
- unsigned int i;
- for (i = 0; i < ARRAY_SIZE(stm32_vrefbuf_voltages); i++) {
- if (uV == stm32_vrefbuf_voltages[i]) {
- clrsetbits_le32(priv->base + STM32_VREFBUF_CSR,
- STM32_VRS, i << STM32_VRS_SHIFT);
- return 0;
- }
- }
- return -EINVAL;
- }
- static int stm32_vrefbuf_get_value(struct udevice *dev)
- {
- struct stm32_vrefbuf *priv = dev_get_priv(dev);
- u32 val;
- val = readl(priv->base + STM32_VREFBUF_CSR) & STM32_VRS;
- val >>= STM32_VRS_SHIFT;
- return stm32_vrefbuf_voltages[val];
- }
- static const struct dm_regulator_ops stm32_vrefbuf_ops = {
- .get_value = stm32_vrefbuf_get_value,
- .set_value = stm32_vrefbuf_set_value,
- .get_enable = stm32_vrefbuf_get_enable,
- .set_enable = stm32_vrefbuf_set_enable,
- };
- static int stm32_vrefbuf_probe(struct udevice *dev)
- {
- struct stm32_vrefbuf *priv = dev_get_priv(dev);
- int ret;
- priv->base = dev_read_addr_ptr(dev);
- ret = clk_get_by_index(dev, 0, &priv->clk);
- if (ret) {
- dev_err(dev, "Can't get clock: %d\n", ret);
- return ret;
- }
- ret = clk_enable(&priv->clk);
- if (ret) {
- dev_err(dev, "Can't enable clock: %d\n", ret);
- return ret;
- }
- ret = device_get_supply_regulator(dev, "vdda-supply",
- &priv->vdda_supply);
- if (ret) {
- dev_dbg(dev, "No vdda-supply: %d\n", ret);
- return 0;
- }
- ret = regulator_set_enable(priv->vdda_supply, true);
- if (ret) {
- dev_err(dev, "Can't enable vdda-supply: %d\n", ret);
- clk_disable(&priv->clk);
- }
- return ret;
- }
- static const struct udevice_id stm32_vrefbuf_ids[] = {
- { .compatible = "st,stm32-vrefbuf" },
- { }
- };
- U_BOOT_DRIVER(stm32_vrefbuf) = {
- .name = "stm32-vrefbuf",
- .id = UCLASS_REGULATOR,
- .of_match = stm32_vrefbuf_ids,
- .probe = stm32_vrefbuf_probe,
- .ops = &stm32_vrefbuf_ops,
- .priv_auto = sizeof(struct stm32_vrefbuf),
- };
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