Add regulator driver for STM32 voltage reference buffer which can be used as voltage reference for ADCs, DACs and external components through dedicated VREF+ pin. Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com> Signed-off-by: Patrice Chotard <patrice.chotard@st.com>lime2-spi
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STM32 VREFBUF - Voltage reference buffer |
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Some STM32 devices embed a voltage reference buffer which can be used as |
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voltage reference for ADCs, DACs and also as voltage reference for external |
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components through the dedicated VREF+ pin. |
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Required properties: |
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- compatible: Must be "st,stm32-vrefbuf". |
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- reg: Offset and length of VREFBUF register set. |
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- clocks: Must contain an entry for peripheral clock. |
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Optional properties: |
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- vdda-supply: Phandle to the parent vdda supply regulator node. |
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Example: |
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vrefbuf: regulator@58003c00 { |
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compatible = "st,stm32-vrefbuf"; |
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reg = <0x58003C00 0x8>; |
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clocks = <&rcc VREF_CK>; |
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regulator-min-microvolt = <1500000>; |
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regulator-max-microvolt = <2500000>; |
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vdda-supply = <&vdda>; |
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}; |
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// SPDX-License-Identifier: GPL-2.0+
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/*
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* Copyright (C) 2018, STMicroelectronics - All Rights Reserved |
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* Author: Fabrice Gasnier <fabrice.gasnier@st.com> |
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* |
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* Originally based on the Linux kernel v4.16 drivers/regulator/stm32-vrefbuf.c |
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*/ |
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#include <common.h> |
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#include <clk.h> |
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#include <dm.h> |
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#include <asm/io.h> |
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#include <linux/iopoll.h> |
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#include <linux/kernel.h> |
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#include <power/regulator.h> |
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/* STM32 VREFBUF registers */ |
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#define STM32_VREFBUF_CSR 0x00 |
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/* STM32 VREFBUF CSR bitfields */ |
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#define STM32_VRS GENMASK(6, 4) |
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#define STM32_VRS_SHIFT 4 |
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#define STM32_VRR BIT(3) |
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#define STM32_HIZ BIT(1) |
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#define STM32_ENVR BIT(0) |
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struct stm32_vrefbuf { |
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void __iomem *base; |
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struct clk clk; |
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struct udevice *vdda_supply; |
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}; |
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static const unsigned int stm32_vrefbuf_voltages[] = { |
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/* Matches resp. VRS = 000b, 001b, 010b, 011b */ |
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2500000, 2048000, 1800000, 1500000, |
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}; |
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static int stm32_vrefbuf_set_enable(struct udevice *dev, bool enable) |
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{ |
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struct stm32_vrefbuf *priv = dev_get_priv(dev); |
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u32 val; |
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int ret; |
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clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_HIZ | STM32_ENVR, |
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enable ? STM32_ENVR : STM32_HIZ); |
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if (!enable) |
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return 0; |
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/*
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* Vrefbuf startup time depends on external capacitor: wait here for |
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* VRR to be set. That means output has reached expected value. |
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* ~650us sleep should be enough for caps up to 1.5uF. Use 10ms as |
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* arbitrary timeout. |
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*/ |
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ret = readl_poll_timeout(priv->base + STM32_VREFBUF_CSR, val, |
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val & STM32_VRR, 10000); |
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if (ret < 0) { |
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dev_err(dev, "stm32 vrefbuf timed out: %d\n", ret); |
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clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, STM32_ENVR, |
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STM32_HIZ); |
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return ret; |
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} |
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return 0; |
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} |
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static int stm32_vrefbuf_get_enable(struct udevice *dev) |
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{ |
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struct stm32_vrefbuf *priv = dev_get_priv(dev); |
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return readl(priv->base + STM32_VREFBUF_CSR) & STM32_ENVR; |
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} |
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static int stm32_vrefbuf_set_value(struct udevice *dev, int uV) |
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{ |
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struct stm32_vrefbuf *priv = dev_get_priv(dev); |
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unsigned int i; |
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for (i = 0; i < ARRAY_SIZE(stm32_vrefbuf_voltages); i++) { |
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if (uV == stm32_vrefbuf_voltages[i]) { |
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clrsetbits_le32(priv->base + STM32_VREFBUF_CSR, |
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STM32_VRS, i << STM32_VRS_SHIFT); |
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return 0; |
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} |
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} |
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return -EINVAL; |
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} |
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static int stm32_vrefbuf_get_value(struct udevice *dev) |
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{ |
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struct stm32_vrefbuf *priv = dev_get_priv(dev); |
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u32 val; |
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val = readl(priv->base + STM32_VREFBUF_CSR) & STM32_VRS; |
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val >>= STM32_VRS_SHIFT; |
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return stm32_vrefbuf_voltages[val]; |
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} |
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static const struct dm_regulator_ops stm32_vrefbuf_ops = { |
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.get_value = stm32_vrefbuf_get_value, |
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.set_value = stm32_vrefbuf_set_value, |
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.get_enable = stm32_vrefbuf_get_enable, |
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.set_enable = stm32_vrefbuf_set_enable, |
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}; |
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static int stm32_vrefbuf_probe(struct udevice *dev) |
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{ |
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struct stm32_vrefbuf *priv = dev_get_priv(dev); |
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int ret; |
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priv->base = dev_read_addr_ptr(dev); |
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ret = clk_get_by_index(dev, 0, &priv->clk); |
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if (ret) { |
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dev_err(dev, "Can't get clock: %d\n", ret); |
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return ret; |
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} |
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ret = clk_enable(&priv->clk); |
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if (ret) { |
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dev_err(dev, "Can't enable clock: %d\n", ret); |
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return ret; |
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} |
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ret = device_get_supply_regulator(dev, "vdda-supply", |
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&priv->vdda_supply); |
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if (ret) { |
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dev_dbg(dev, "No vdda-supply: %d\n", ret); |
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return 0; |
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} |
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ret = regulator_set_enable(priv->vdda_supply, true); |
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if (ret) { |
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dev_err(dev, "Can't enable vdda-supply: %d\n", ret); |
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clk_disable(&priv->clk); |
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} |
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return ret; |
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} |
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static const struct udevice_id stm32_vrefbuf_ids[] = { |
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{ .compatible = "st,stm32-vrefbuf" }, |
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{ } |
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}; |
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U_BOOT_DRIVER(stm32_vrefbuf) = { |
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.name = "stm32-vrefbuf", |
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.id = UCLASS_REGULATOR, |
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.of_match = stm32_vrefbuf_ids, |
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.probe = stm32_vrefbuf_probe, |
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.ops = &stm32_vrefbuf_ops, |
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.priv_auto_alloc_size = sizeof(struct stm32_vrefbuf), |
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}; |
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