diff options
Diffstat (limited to 'kernel/drivers/reset/sti/reset-syscfg.c')
| -rw-r--r-- | kernel/drivers/reset/sti/reset-syscfg.c | 186 |
1 files changed, 186 insertions, 0 deletions
diff --git a/kernel/drivers/reset/sti/reset-syscfg.c b/kernel/drivers/reset/sti/reset-syscfg.c new file mode 100644 index 000000000..a145cc066 --- /dev/null +++ b/kernel/drivers/reset/sti/reset-syscfg.c @@ -0,0 +1,186 @@ +/* + * Copyright (C) 2013 STMicroelectronics Limited + * Author: Stephen Gallimore <stephen.gallimore@st.com> + * + * Inspired by mach-imx/src.c + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + */ +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/module.h> +#include <linux/err.h> +#include <linux/types.h> +#include <linux/of_device.h> +#include <linux/regmap.h> +#include <linux/mfd/syscon.h> + +#include "reset-syscfg.h" + +/** + * Reset channel regmap configuration + * + * @reset: regmap field for the channel's reset bit. + * @ack: regmap field for the channel's ack bit (optional). + */ +struct syscfg_reset_channel { + struct regmap_field *reset; + struct regmap_field *ack; +}; + +/** + * A reset controller which groups together a set of related reset bits, which + * may be located in different system configuration registers. + * + * @rst: base reset controller structure. + * @active_low: are the resets in this controller active low, i.e. clearing + * the reset bit puts the hardware into reset. + * @channels: An array of reset channels for this controller. + */ +struct syscfg_reset_controller { + struct reset_controller_dev rst; + bool active_low; + struct syscfg_reset_channel *channels; +}; + +#define to_syscfg_reset_controller(_rst) \ + container_of(_rst, struct syscfg_reset_controller, rst) + +static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev, + unsigned long idx, int assert) +{ + struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev); + const struct syscfg_reset_channel *ch; + u32 ctrl_val = rst->active_low ? !assert : !!assert; + int err; + + if (idx >= rcdev->nr_resets) + return -EINVAL; + + ch = &rst->channels[idx]; + + err = regmap_field_write(ch->reset, ctrl_val); + if (err) + return err; + + if (ch->ack) { + unsigned long timeout = jiffies + msecs_to_jiffies(1000); + u32 ack_val; + + while (true) { + err = regmap_field_read(ch->ack, &ack_val); + if (err) + return err; + + if (ack_val == ctrl_val) + break; + + if (time_after(jiffies, timeout)) + return -ETIME; + + cpu_relax(); + } + } + + return 0; +} + +static int syscfg_reset_assert(struct reset_controller_dev *rcdev, + unsigned long idx) +{ + return syscfg_reset_program_hw(rcdev, idx, true); +} + +static int syscfg_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long idx) +{ + return syscfg_reset_program_hw(rcdev, idx, false); +} + +static int syscfg_reset_dev(struct reset_controller_dev *rcdev, + unsigned long idx) +{ + int err = syscfg_reset_assert(rcdev, idx); + if (err) + return err; + + return syscfg_reset_deassert(rcdev, idx); +} + +static struct reset_control_ops syscfg_reset_ops = { + .reset = syscfg_reset_dev, + .assert = syscfg_reset_assert, + .deassert = syscfg_reset_deassert, +}; + +static int syscfg_reset_controller_register(struct device *dev, + const struct syscfg_reset_controller_data *data) +{ + struct syscfg_reset_controller *rc; + size_t size; + int i, err; + + rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL); + if (!rc) + return -ENOMEM; + + size = sizeof(struct syscfg_reset_channel) * data->nr_channels; + + rc->channels = devm_kzalloc(dev, size, GFP_KERNEL); + if (!rc->channels) + return -ENOMEM; + + rc->rst.ops = &syscfg_reset_ops, + rc->rst.of_node = dev->of_node; + rc->rst.nr_resets = data->nr_channels; + rc->active_low = data->active_low; + + for (i = 0; i < data->nr_channels; i++) { + struct regmap *map; + struct regmap_field *f; + const char *compatible = data->channels[i].compatible; + + map = syscon_regmap_lookup_by_compatible(compatible); + if (IS_ERR(map)) + return PTR_ERR(map); + + f = devm_regmap_field_alloc(dev, map, data->channels[i].reset); + if (IS_ERR(f)) + return PTR_ERR(f); + + rc->channels[i].reset = f; + + if (!data->wait_for_ack) + continue; + + f = devm_regmap_field_alloc(dev, map, data->channels[i].ack); + if (IS_ERR(f)) + return PTR_ERR(f); + + rc->channels[i].ack = f; + } + + err = reset_controller_register(&rc->rst); + if (!err) + dev_info(dev, "registered\n"); + + return err; +} + +int syscfg_reset_probe(struct platform_device *pdev) +{ + struct device *dev = pdev ? &pdev->dev : NULL; + const struct of_device_id *match; + + if (!dev || !dev->driver) + return -ENODEV; + + match = of_match_device(dev->driver->of_match_table, dev); + if (!match || !match->data) + return -EINVAL; + + return syscfg_reset_controller_register(dev, match->data); +} |