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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
*/
#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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