diff options
Diffstat (limited to 'drivers/devfreq/imx8m-ddrc.c')
| -rw-r--r-- | drivers/devfreq/imx8m-ddrc.c | 457 |
1 files changed, 457 insertions, 0 deletions
diff --git a/drivers/devfreq/imx8m-ddrc.c b/drivers/devfreq/imx8m-ddrc.c new file mode 100644 index 000000000..16636973e --- /dev/null +++ b/drivers/devfreq/imx8m-ddrc.c @@ -0,0 +1,457 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2019 NXP + */ + +#include <linux/module.h> +#include <linux/device.h> +#include <linux/of_device.h> +#include <linux/platform_device.h> +#include <linux/devfreq.h> +#include <linux/pm_opp.h> +#include <linux/clk.h> +#include <linux/clk-provider.h> +#include <linux/arm-smccc.h> + +#define IMX_SIP_DDR_DVFS 0xc2000004 + +/* Query available frequencies. */ +#define IMX_SIP_DDR_DVFS_GET_FREQ_COUNT 0x10 +#define IMX_SIP_DDR_DVFS_GET_FREQ_INFO 0x11 + +/* + * This should be in a 1:1 mapping with devicetree OPPs but + * firmware provides additional info. + */ +struct imx8m_ddrc_freq { + unsigned long rate; + unsigned long smcarg; + int dram_core_parent_index; + int dram_alt_parent_index; + int dram_apb_parent_index; +}; + +/* Hardware limitation */ +#define IMX8M_DDRC_MAX_FREQ_COUNT 4 + +/* + * i.MX8M DRAM Controller clocks have the following structure (abridged): + * + * +----------+ |\ +------+ + * | dram_pll |-------|M| dram_core | | + * +----------+ |U|---------->| D | + * /--|X| | D | + * dram_alt_root | |/ | R | + * | | C | + * +---------+ | | + * |FIX DIV/4| | | + * +---------+ | | + * composite: | | | + * +----------+ | | | + * | dram_alt |----/ | | + * +----------+ | | + * | dram_apb |-------------------->| | + * +----------+ +------+ + * + * The dram_pll is used for higher rates and dram_alt is used for lower rates. + * + * Frequency switching is implemented in TF-A (via SMC call) and can change the + * configuration of the clocks, including mux parents. The dram_alt and + * dram_apb clocks are "imx composite" and their parent can change too. + * + * We need to prepare/enable the new mux parents head of switching and update + * their information afterwards. + */ +struct imx8m_ddrc { + struct devfreq_dev_profile profile; + struct devfreq *devfreq; + + /* For frequency switching: */ + struct clk *dram_core; + struct clk *dram_pll; + struct clk *dram_alt; + struct clk *dram_apb; + + int freq_count; + struct imx8m_ddrc_freq freq_table[IMX8M_DDRC_MAX_FREQ_COUNT]; +}; + +static struct imx8m_ddrc_freq *imx8m_ddrc_find_freq(struct imx8m_ddrc *priv, + unsigned long rate) +{ + struct imx8m_ddrc_freq *freq; + int i; + + /* + * Firmware reports values in MT/s, so we round-down from Hz + * Rounding is extra generous to ensure a match. + */ + rate = DIV_ROUND_CLOSEST(rate, 250000); + for (i = 0; i < priv->freq_count; ++i) { + freq = &priv->freq_table[i]; + if (freq->rate == rate || + freq->rate + 1 == rate || + freq->rate - 1 == rate) + return freq; + } + + return NULL; +} + +static void imx8m_ddrc_smc_set_freq(int target_freq) +{ + struct arm_smccc_res res; + u32 online_cpus = 0; + int cpu; + + local_irq_disable(); + + for_each_online_cpu(cpu) + online_cpus |= (1 << (cpu * 8)); + + /* change the ddr freqency */ + arm_smccc_smc(IMX_SIP_DDR_DVFS, target_freq, online_cpus, + 0, 0, 0, 0, 0, &res); + + local_irq_enable(); +} + +static struct clk *clk_get_parent_by_index(struct clk *clk, int index) +{ + struct clk_hw *hw; + + hw = clk_hw_get_parent_by_index(__clk_get_hw(clk), index); + + return hw ? hw->clk : NULL; +} + +static int imx8m_ddrc_set_freq(struct device *dev, struct imx8m_ddrc_freq *freq) +{ + struct imx8m_ddrc *priv = dev_get_drvdata(dev); + struct clk *new_dram_core_parent; + struct clk *new_dram_alt_parent; + struct clk *new_dram_apb_parent; + int ret; + + /* + * Fetch new parents + * + * new_dram_alt_parent and new_dram_apb_parent are optional but + * new_dram_core_parent is not. + */ + new_dram_core_parent = clk_get_parent_by_index( + priv->dram_core, freq->dram_core_parent_index - 1); + if (!new_dram_core_parent) { + dev_err(dev, "failed to fetch new dram_core parent\n"); + return -EINVAL; + } + if (freq->dram_alt_parent_index) { + new_dram_alt_parent = clk_get_parent_by_index( + priv->dram_alt, + freq->dram_alt_parent_index - 1); + if (!new_dram_alt_parent) { + dev_err(dev, "failed to fetch new dram_alt parent\n"); + return -EINVAL; + } + } else + new_dram_alt_parent = NULL; + + if (freq->dram_apb_parent_index) { + new_dram_apb_parent = clk_get_parent_by_index( + priv->dram_apb, + freq->dram_apb_parent_index - 1); + if (!new_dram_apb_parent) { + dev_err(dev, "failed to fetch new dram_apb parent\n"); + return -EINVAL; + } + } else + new_dram_apb_parent = NULL; + + /* increase reference counts and ensure clks are ON before switch */ + ret = clk_prepare_enable(new_dram_core_parent); + if (ret) { + dev_err(dev, "failed to enable new dram_core parent: %d\n", + ret); + goto out; + } + ret = clk_prepare_enable(new_dram_alt_parent); + if (ret) { + dev_err(dev, "failed to enable new dram_alt parent: %d\n", + ret); + goto out_disable_core_parent; + } + ret = clk_prepare_enable(new_dram_apb_parent); + if (ret) { + dev_err(dev, "failed to enable new dram_apb parent: %d\n", + ret); + goto out_disable_alt_parent; + } + + imx8m_ddrc_smc_set_freq(freq->smcarg); + + /* update parents in clk tree after switch. */ + ret = clk_set_parent(priv->dram_core, new_dram_core_parent); + if (ret) + dev_warn(dev, "failed to set dram_core parent: %d\n", ret); + if (new_dram_alt_parent) { + ret = clk_set_parent(priv->dram_alt, new_dram_alt_parent); + if (ret) + dev_warn(dev, "failed to set dram_alt parent: %d\n", + ret); + } + if (new_dram_apb_parent) { + ret = clk_set_parent(priv->dram_apb, new_dram_apb_parent); + if (ret) + dev_warn(dev, "failed to set dram_apb parent: %d\n", + ret); + } + + /* + * Explicitly refresh dram PLL rate. + * + * Even if it's marked with CLK_GET_RATE_NOCACHE the rate will not be + * automatically refreshed when clk_get_rate is called on children. + */ + clk_get_rate(priv->dram_pll); + + /* + * clk_set_parent transfer the reference count from old parent. + * now we drop extra reference counts used during the switch + */ + clk_disable_unprepare(new_dram_apb_parent); +out_disable_alt_parent: + clk_disable_unprepare(new_dram_alt_parent); +out_disable_core_parent: + clk_disable_unprepare(new_dram_core_parent); +out: + return ret; +} + +static int imx8m_ddrc_target(struct device *dev, unsigned long *freq, u32 flags) +{ + struct imx8m_ddrc *priv = dev_get_drvdata(dev); + struct imx8m_ddrc_freq *freq_info; + struct dev_pm_opp *new_opp; + unsigned long old_freq, new_freq; + int ret; + + new_opp = devfreq_recommended_opp(dev, freq, flags); + if (IS_ERR(new_opp)) { + ret = PTR_ERR(new_opp); + dev_err(dev, "failed to get recommended opp: %d\n", ret); + return ret; + } + dev_pm_opp_put(new_opp); + + old_freq = clk_get_rate(priv->dram_core); + if (*freq == old_freq) + return 0; + + freq_info = imx8m_ddrc_find_freq(priv, *freq); + if (!freq_info) + return -EINVAL; + + /* + * Read back the clk rate to verify switch was correct and so that + * we can report it on all error paths. + */ + ret = imx8m_ddrc_set_freq(dev, freq_info); + + new_freq = clk_get_rate(priv->dram_core); + if (ret) + dev_err(dev, "ddrc failed freq switch to %lu from %lu: error %d. now at %lu\n", + *freq, old_freq, ret, new_freq); + else if (*freq != new_freq) + dev_err(dev, "ddrc failed freq update to %lu from %lu, now at %lu\n", + *freq, old_freq, new_freq); + else + dev_dbg(dev, "ddrc freq set to %lu (was %lu)\n", + *freq, old_freq); + + return ret; +} + +static int imx8m_ddrc_get_cur_freq(struct device *dev, unsigned long *freq) +{ + struct imx8m_ddrc *priv = dev_get_drvdata(dev); + + *freq = clk_get_rate(priv->dram_core); + + return 0; +} + +static int imx8m_ddrc_init_freq_info(struct device *dev) +{ + struct imx8m_ddrc *priv = dev_get_drvdata(dev); + struct arm_smccc_res res; + int index; + + /* An error here means DDR DVFS API not supported by firmware */ + arm_smccc_smc(IMX_SIP_DDR_DVFS, IMX_SIP_DDR_DVFS_GET_FREQ_COUNT, + 0, 0, 0, 0, 0, 0, &res); + priv->freq_count = res.a0; + if (priv->freq_count <= 0 || + priv->freq_count > IMX8M_DDRC_MAX_FREQ_COUNT) + return -ENODEV; + + for (index = 0; index < priv->freq_count; ++index) { + struct imx8m_ddrc_freq *freq = &priv->freq_table[index]; + + arm_smccc_smc(IMX_SIP_DDR_DVFS, IMX_SIP_DDR_DVFS_GET_FREQ_INFO, + index, 0, 0, 0, 0, 0, &res); + /* Result should be strictly positive */ + if ((long)res.a0 <= 0) + return -ENODEV; + + freq->rate = res.a0; + freq->smcarg = index; + freq->dram_core_parent_index = res.a1; + freq->dram_alt_parent_index = res.a2; + freq->dram_apb_parent_index = res.a3; + + /* dram_core has 2 options: dram_pll or dram_alt_root */ + if (freq->dram_core_parent_index != 1 && + freq->dram_core_parent_index != 2) + return -ENODEV; + /* dram_apb and dram_alt have exactly 8 possible parents */ + if (freq->dram_alt_parent_index > 8 || + freq->dram_apb_parent_index > 8) + return -ENODEV; + /* dram_core from alt requires explicit dram_alt parent */ + if (freq->dram_core_parent_index == 2 && + freq->dram_alt_parent_index == 0) + return -ENODEV; + } + + return 0; +} + +static int imx8m_ddrc_check_opps(struct device *dev) +{ + struct imx8m_ddrc *priv = dev_get_drvdata(dev); + struct imx8m_ddrc_freq *freq_info; + struct dev_pm_opp *opp; + unsigned long freq; + int i, opp_count; + + /* Enumerate DT OPPs and disable those not supported by firmware */ + opp_count = dev_pm_opp_get_opp_count(dev); + if (opp_count < 0) + return opp_count; + for (i = 0, freq = 0; i < opp_count; ++i, ++freq) { + opp = dev_pm_opp_find_freq_ceil(dev, &freq); + if (IS_ERR(opp)) { + dev_err(dev, "Failed enumerating OPPs: %ld\n", + PTR_ERR(opp)); + return PTR_ERR(opp); + } + dev_pm_opp_put(opp); + + freq_info = imx8m_ddrc_find_freq(priv, freq); + if (!freq_info) { + dev_info(dev, "Disable unsupported OPP %luHz %luMT/s\n", + freq, DIV_ROUND_CLOSEST(freq, 250000)); + dev_pm_opp_disable(dev, freq); + } + } + + return 0; +} + +static void imx8m_ddrc_exit(struct device *dev) +{ + dev_pm_opp_of_remove_table(dev); +} + +static int imx8m_ddrc_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct imx8m_ddrc *priv; + const char *gov = DEVFREQ_GOV_USERSPACE; + int ret; + + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + platform_set_drvdata(pdev, priv); + + ret = imx8m_ddrc_init_freq_info(dev); + if (ret) { + dev_err(dev, "failed to init firmware freq info: %d\n", ret); + return ret; + } + + priv->dram_core = devm_clk_get(dev, "core"); + if (IS_ERR(priv->dram_core)) { + ret = PTR_ERR(priv->dram_core); + dev_err(dev, "failed to fetch core clock: %d\n", ret); + return ret; + } + priv->dram_pll = devm_clk_get(dev, "pll"); + if (IS_ERR(priv->dram_pll)) { + ret = PTR_ERR(priv->dram_pll); + dev_err(dev, "failed to fetch pll clock: %d\n", ret); + return ret; + } + priv->dram_alt = devm_clk_get(dev, "alt"); + if (IS_ERR(priv->dram_alt)) { + ret = PTR_ERR(priv->dram_alt); + dev_err(dev, "failed to fetch alt clock: %d\n", ret); + return ret; + } + priv->dram_apb = devm_clk_get(dev, "apb"); + if (IS_ERR(priv->dram_apb)) { + ret = PTR_ERR(priv->dram_apb); + dev_err(dev, "failed to fetch apb clock: %d\n", ret); + return ret; + } + + ret = dev_pm_opp_of_add_table(dev); + if (ret < 0) { + dev_err(dev, "failed to get OPP table\n"); + return ret; + } + + ret = imx8m_ddrc_check_opps(dev); + if (ret < 0) + goto err; + + priv->profile.target = imx8m_ddrc_target; + priv->profile.exit = imx8m_ddrc_exit; + priv->profile.get_cur_freq = imx8m_ddrc_get_cur_freq; + priv->profile.initial_freq = clk_get_rate(priv->dram_core); + + priv->devfreq = devm_devfreq_add_device(dev, &priv->profile, + gov, NULL); + if (IS_ERR(priv->devfreq)) { + ret = PTR_ERR(priv->devfreq); + dev_err(dev, "failed to add devfreq device: %d\n", ret); + goto err; + } + + return 0; + +err: + dev_pm_opp_of_remove_table(dev); + return ret; +} + +static const struct of_device_id imx8m_ddrc_of_match[] = { + { .compatible = "fsl,imx8m-ddrc", }, + { /* sentinel */ }, +}; +MODULE_DEVICE_TABLE(of, imx8m_ddrc_of_match); + +static struct platform_driver imx8m_ddrc_platdrv = { + .probe = imx8m_ddrc_probe, + .driver = { + .name = "imx8m-ddrc-devfreq", + .of_match_table = imx8m_ddrc_of_match, + }, +}; +module_platform_driver(imx8m_ddrc_platdrv); + +MODULE_DESCRIPTION("i.MX8M DDR Controller frequency driver"); +MODULE_AUTHOR("Leonard Crestez <leonard.crestez@nxp.com>"); +MODULE_LICENSE("GPL v2"); |