diff options
Diffstat (limited to 'drivers/clk/ux500/reset-prcc.c')
| -rw-r--r-- | drivers/clk/ux500/reset-prcc.c | 181 |
1 files changed, 181 insertions, 0 deletions
diff --git a/drivers/clk/ux500/reset-prcc.c b/drivers/clk/ux500/reset-prcc.c new file mode 100644 index 0000000000..f7e48941fb --- /dev/null +++ b/drivers/clk/ux500/reset-prcc.c @@ -0,0 +1,181 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Reset controller portions for the U8500 PRCC + * Copyright (C) 2021 Linus Walleij <linus.walleij@linaro.org> + */ +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/slab.h> +#include <linux/io.h> +#include <linux/err.h> +#include <linux/types.h> +#include <linux/reset-controller.h> +#include <linux/bits.h> +#include <linux/delay.h> + +#include "prcc.h" +#include "reset-prcc.h" + +#define to_u8500_prcc_reset(p) container_of((p), struct u8500_prcc_reset, rcdev) + +/* This macro flattens the 2-dimensional PRCC numberspace */ +#define PRCC_RESET_LINE(prcc_num, bit) \ + (((prcc_num) * PRCC_PERIPHS_PER_CLUSTER) + (bit)) + +/* + * Reset registers in each PRCC - the reset lines are active low + * so what you need to do is write a bit for the peripheral you + * want to put into reset into the CLEAR register, this will assert + * the reset by pulling the line low. SET take the device out of + * reset. The status reflects the actual state of the line. + */ +#define PRCC_K_SOFTRST_SET 0x018 +#define PRCC_K_SOFTRST_CLEAR 0x01c +#define PRCC_K_RST_STATUS 0x020 + +static int prcc_num_to_index(unsigned int num) +{ + switch (num) { + case 1: + return CLKRST1_INDEX; + case 2: + return CLKRST2_INDEX; + case 3: + return CLKRST3_INDEX; + case 5: + return CLKRST5_INDEX; + case 6: + return CLKRST6_INDEX; + } + return -EINVAL; +} + +static void __iomem *u8500_prcc_reset_base(struct u8500_prcc_reset *ur, + unsigned long id) +{ + unsigned int prcc_num, index; + + prcc_num = id / PRCC_PERIPHS_PER_CLUSTER; + index = prcc_num_to_index(prcc_num); + + if (index >= ARRAY_SIZE(ur->base)) + return NULL; + + return ur->base[index]; +} + +static int u8500_prcc_reset(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct u8500_prcc_reset *ur = to_u8500_prcc_reset(rcdev); + void __iomem *base = u8500_prcc_reset_base(ur, id); + unsigned int bit = id % PRCC_PERIPHS_PER_CLUSTER; + + pr_debug("PRCC cycle reset id %lu, bit %u\n", id, bit); + + /* + * Assert reset and then release it. The one microsecond + * delay is found in the vendor reference code. + */ + writel(BIT(bit), base + PRCC_K_SOFTRST_CLEAR); + udelay(1); + writel(BIT(bit), base + PRCC_K_SOFTRST_SET); + udelay(1); + + return 0; +} + +static int u8500_prcc_reset_assert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct u8500_prcc_reset *ur = to_u8500_prcc_reset(rcdev); + void __iomem *base = u8500_prcc_reset_base(ur, id); + unsigned int bit = id % PRCC_PERIPHS_PER_CLUSTER; + + pr_debug("PRCC assert reset id %lu, bit %u\n", id, bit); + writel(BIT(bit), base + PRCC_K_SOFTRST_CLEAR); + + return 0; +} + +static int u8500_prcc_reset_deassert(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct u8500_prcc_reset *ur = to_u8500_prcc_reset(rcdev); + void __iomem *base = u8500_prcc_reset_base(ur, id); + unsigned int bit = id % PRCC_PERIPHS_PER_CLUSTER; + + pr_debug("PRCC deassert reset id %lu, bit %u\n", id, bit); + writel(BIT(bit), base + PRCC_K_SOFTRST_SET); + + return 0; +} + +static int u8500_prcc_reset_status(struct reset_controller_dev *rcdev, + unsigned long id) +{ + struct u8500_prcc_reset *ur = to_u8500_prcc_reset(rcdev); + void __iomem *base = u8500_prcc_reset_base(ur, id); + unsigned int bit = id % PRCC_PERIPHS_PER_CLUSTER; + u32 val; + + pr_debug("PRCC check status on reset line id %lu, bit %u\n", id, bit); + val = readl(base + PRCC_K_RST_STATUS); + + /* Active low so return the inverse value of the bit */ + return !(val & BIT(bit)); +} + +static const struct reset_control_ops u8500_prcc_reset_ops = { + .reset = u8500_prcc_reset, + .assert = u8500_prcc_reset_assert, + .deassert = u8500_prcc_reset_deassert, + .status = u8500_prcc_reset_status, +}; + +static int u8500_prcc_reset_xlate(struct reset_controller_dev *rcdev, + const struct of_phandle_args *reset_spec) +{ + unsigned int prcc_num, bit; + + if (reset_spec->args_count != 2) + return -EINVAL; + + prcc_num = reset_spec->args[0]; + bit = reset_spec->args[1]; + + if (prcc_num != 1 && prcc_num != 2 && prcc_num != 3 && + prcc_num != 5 && prcc_num != 6) { + pr_err("%s: invalid PRCC %d\n", __func__, prcc_num); + return -EINVAL; + } + + pr_debug("located reset line %d at PRCC %d bit %d\n", + PRCC_RESET_LINE(prcc_num, bit), prcc_num, bit); + + return PRCC_RESET_LINE(prcc_num, bit); +} + +void u8500_prcc_reset_init(struct device_node *np, struct u8500_prcc_reset *ur) +{ + struct reset_controller_dev *rcdev = &ur->rcdev; + int ret; + int i; + + for (i = 0; i < CLKRST_MAX; i++) { + ur->base[i] = ioremap(ur->phy_base[i], SZ_4K); + if (!ur->base[i]) + pr_err("PRCC failed to remap for reset base %d (%08x)\n", + i, ur->phy_base[i]); + } + + rcdev->owner = THIS_MODULE; + rcdev->ops = &u8500_prcc_reset_ops; + rcdev->of_node = np; + rcdev->of_reset_n_cells = 2; + rcdev->of_xlate = u8500_prcc_reset_xlate; + + ret = reset_controller_register(rcdev); + if (ret) + pr_err("PRCC failed to register reset controller\n"); +} |