diff options
Diffstat (limited to '')
| -rw-r--r-- | drivers/clk/tegra/clk-tegra210-emc.c | 371 |
1 files changed, 371 insertions, 0 deletions
diff --git a/drivers/clk/tegra/clk-tegra210-emc.c b/drivers/clk/tegra/clk-tegra210-emc.c new file mode 100644 index 000000000..672ca8c18 --- /dev/null +++ b/drivers/clk/tegra/clk-tegra210-emc.c @@ -0,0 +1,371 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (c) 2015-2020, NVIDIA CORPORATION. All rights reserved. + */ + +#include <linux/bitfield.h> +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/clk/tegra.h> +#include <linux/device.h> +#include <linux/module.h> +#include <linux/io.h> +#include <linux/slab.h> + +#include "clk.h" + +#define CLK_SOURCE_EMC 0x19c +#define CLK_SOURCE_EMC_2X_CLK_SRC GENMASK(31, 29) +#define CLK_SOURCE_EMC_MC_EMC_SAME_FREQ BIT(16) +#define CLK_SOURCE_EMC_2X_CLK_DIVISOR GENMASK(7, 0) + +#define CLK_SRC_PLLM 0 +#define CLK_SRC_PLLC 1 +#define CLK_SRC_PLLP 2 +#define CLK_SRC_CLK_M 3 +#define CLK_SRC_PLLM_UD 4 +#define CLK_SRC_PLLMB_UD 5 +#define CLK_SRC_PLLMB 6 +#define CLK_SRC_PLLP_UD 7 + +struct tegra210_clk_emc { + struct clk_hw hw; + void __iomem *regs; + + struct tegra210_clk_emc_provider *provider; + + struct clk *parents[8]; +}; + +static inline struct tegra210_clk_emc * +to_tegra210_clk_emc(struct clk_hw *hw) +{ + return container_of(hw, struct tegra210_clk_emc, hw); +} + +static const char *tegra210_clk_emc_parents[] = { + "pll_m", "pll_c", "pll_p", "clk_m", "pll_m_ud", "pll_mb_ud", + "pll_mb", "pll_p_ud", +}; + +static u8 tegra210_clk_emc_get_parent(struct clk_hw *hw) +{ + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw); + u32 value; + u8 src; + + value = readl_relaxed(emc->regs + CLK_SOURCE_EMC); + src = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, value); + + return src; +} + +static unsigned long tegra210_clk_emc_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw); + u32 value, div; + + /* + * CCF assumes that neither the parent nor its rate will change during + * ->set_rate(), so the parent rate passed in here was cached from the + * parent before the ->set_rate() call. + * + * This can lead to wrong results being reported for the EMC clock if + * the parent and/or parent rate have changed as part of the EMC rate + * change sequence. Fix this by overriding the parent clock with what + * we know to be the correct value after the rate change. + */ + parent_rate = clk_hw_get_rate(clk_hw_get_parent(hw)); + + value = readl_relaxed(emc->regs + CLK_SOURCE_EMC); + + div = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_DIVISOR, value); + div += 2; + + return DIV_ROUND_UP(parent_rate * 2, div); +} + +static long tegra210_clk_emc_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *prate) +{ + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw); + struct tegra210_clk_emc_provider *provider = emc->provider; + unsigned int i; + + if (!provider || !provider->configs || provider->num_configs == 0) + return clk_hw_get_rate(hw); + + for (i = 0; i < provider->num_configs; i++) { + if (provider->configs[i].rate >= rate) + return provider->configs[i].rate; + } + + return provider->configs[i - 1].rate; +} + +static struct clk *tegra210_clk_emc_find_parent(struct tegra210_clk_emc *emc, + u8 index) +{ + struct clk_hw *parent = clk_hw_get_parent_by_index(&emc->hw, index); + const char *name = clk_hw_get_name(parent); + + /* XXX implement cache? */ + + return __clk_lookup(name); +} + +static int tegra210_clk_emc_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw); + struct tegra210_clk_emc_provider *provider = emc->provider; + struct tegra210_clk_emc_config *config; + struct device *dev = provider->dev; + struct clk_hw *old, *new, *parent; + u8 old_idx, new_idx, index; + struct clk *clk; + unsigned int i; + int err; + + if (!provider->configs || provider->num_configs == 0) + return -EINVAL; + + for (i = 0; i < provider->num_configs; i++) { + if (provider->configs[i].rate >= rate) { + config = &provider->configs[i]; + break; + } + } + + if (i == provider->num_configs) + config = &provider->configs[i - 1]; + + old_idx = tegra210_clk_emc_get_parent(hw); + new_idx = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, config->value); + + old = clk_hw_get_parent_by_index(hw, old_idx); + new = clk_hw_get_parent_by_index(hw, new_idx); + + /* if the rate has changed... */ + if (config->parent_rate != clk_hw_get_rate(old)) { + /* ... but the clock source remains the same ... */ + if (new_idx == old_idx) { + /* ... switch to the alternative clock source. */ + switch (new_idx) { + case CLK_SRC_PLLM: + new_idx = CLK_SRC_PLLMB; + break; + + case CLK_SRC_PLLM_UD: + new_idx = CLK_SRC_PLLMB_UD; + break; + + case CLK_SRC_PLLMB_UD: + new_idx = CLK_SRC_PLLM_UD; + break; + + case CLK_SRC_PLLMB: + new_idx = CLK_SRC_PLLM; + break; + } + + /* + * This should never happen because we can't deal with + * it. + */ + if (WARN_ON(new_idx == old_idx)) + return -EINVAL; + + new = clk_hw_get_parent_by_index(hw, new_idx); + } + + index = new_idx; + parent = new; + } else { + index = old_idx; + parent = old; + } + + clk = tegra210_clk_emc_find_parent(emc, index); + if (IS_ERR(clk)) { + err = PTR_ERR(clk); + dev_err(dev, "failed to get parent clock for index %u: %d\n", + index, err); + return err; + } + + /* set the new parent clock to the required rate */ + if (clk_get_rate(clk) != config->parent_rate) { + err = clk_set_rate(clk, config->parent_rate); + if (err < 0) { + dev_err(dev, "failed to set rate %lu Hz for %pC: %d\n", + config->parent_rate, clk, err); + return err; + } + } + + /* enable the new parent clock */ + if (parent != old) { + err = clk_prepare_enable(clk); + if (err < 0) { + dev_err(dev, "failed to enable parent clock %pC: %d\n", + clk, err); + return err; + } + } + + /* update the EMC source configuration to reflect the new parent */ + config->value &= ~CLK_SOURCE_EMC_2X_CLK_SRC; + config->value |= FIELD_PREP(CLK_SOURCE_EMC_2X_CLK_SRC, index); + + /* + * Finally, switch the EMC programming with both old and new parent + * clocks enabled. + */ + err = provider->set_rate(dev, config); + if (err < 0) { + dev_err(dev, "failed to set EMC rate to %lu Hz: %d\n", rate, + err); + + /* + * If we're unable to switch to the new EMC frequency, we no + * longer need the new parent to be enabled. + */ + if (parent != old) + clk_disable_unprepare(clk); + + return err; + } + + /* reparent to new parent clock and disable the old parent clock */ + if (parent != old) { + clk = tegra210_clk_emc_find_parent(emc, old_idx); + if (IS_ERR(clk)) { + err = PTR_ERR(clk); + dev_err(dev, + "failed to get parent clock for index %u: %d\n", + old_idx, err); + return err; + } + + clk_hw_reparent(hw, parent); + clk_disable_unprepare(clk); + } + + return err; +} + +static const struct clk_ops tegra210_clk_emc_ops = { + .get_parent = tegra210_clk_emc_get_parent, + .recalc_rate = tegra210_clk_emc_recalc_rate, + .round_rate = tegra210_clk_emc_round_rate, + .set_rate = tegra210_clk_emc_set_rate, +}; + +struct clk *tegra210_clk_register_emc(struct device_node *np, + void __iomem *regs) +{ + struct tegra210_clk_emc *emc; + struct clk_init_data init; + struct clk *clk; + + emc = kzalloc(sizeof(*emc), GFP_KERNEL); + if (!emc) + return ERR_PTR(-ENOMEM); + + emc->regs = regs; + + init.name = "emc"; + init.ops = &tegra210_clk_emc_ops; + init.flags = CLK_IS_CRITICAL | CLK_GET_RATE_NOCACHE; + init.parent_names = tegra210_clk_emc_parents; + init.num_parents = ARRAY_SIZE(tegra210_clk_emc_parents); + emc->hw.init = &init; + + clk = clk_register(NULL, &emc->hw); + if (IS_ERR(clk)) { + kfree(emc); + return clk; + } + + return clk; +} + +int tegra210_clk_emc_attach(struct clk *clk, + struct tegra210_clk_emc_provider *provider) +{ + struct clk_hw *hw = __clk_get_hw(clk); + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(hw); + struct device *dev = provider->dev; + unsigned int i; + int err; + + if (!try_module_get(provider->owner)) + return -ENODEV; + + for (i = 0; i < provider->num_configs; i++) { + struct tegra210_clk_emc_config *config = &provider->configs[i]; + struct clk_hw *parent; + bool same_freq; + u8 div, src; + + div = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_DIVISOR, config->value); + src = FIELD_GET(CLK_SOURCE_EMC_2X_CLK_SRC, config->value); + + /* do basic sanity checking on the EMC timings */ + if (div & 0x1) { + dev_err(dev, "invalid odd divider %u for rate %lu Hz\n", + div, config->rate); + err = -EINVAL; + goto put; + } + + same_freq = config->value & CLK_SOURCE_EMC_MC_EMC_SAME_FREQ; + + if (same_freq != config->same_freq) { + dev_err(dev, + "ambiguous EMC to MC ratio for rate %lu Hz\n", + config->rate); + err = -EINVAL; + goto put; + } + + parent = clk_hw_get_parent_by_index(hw, src); + config->parent = src; + + if (src == CLK_SRC_PLLM || src == CLK_SRC_PLLM_UD) { + config->parent_rate = config->rate * (1 + div / 2); + } else { + unsigned long rate = config->rate * (1 + div / 2); + + config->parent_rate = clk_hw_get_rate(parent); + + if (config->parent_rate != rate) { + dev_err(dev, + "rate %lu Hz does not match input\n", + config->rate); + err = -EINVAL; + goto put; + } + } + } + + emc->provider = provider; + + return 0; + +put: + module_put(provider->owner); + return err; +} +EXPORT_SYMBOL_GPL(tegra210_clk_emc_attach); + +void tegra210_clk_emc_detach(struct clk *clk) +{ + struct tegra210_clk_emc *emc = to_tegra210_clk_emc(__clk_get_hw(clk)); + + module_put(emc->provider->owner); + emc->provider = NULL; +} +EXPORT_SYMBOL_GPL(tegra210_clk_emc_detach); |