diff options
Diffstat (limited to 'drivers/memory/tegra/tegra20-emc.c')
| -rw-r--r-- | drivers/memory/tegra/tegra20-emc.c | 90 |
1 files changed, 90 insertions, 0 deletions
diff --git a/drivers/memory/tegra/tegra20-emc.c b/drivers/memory/tegra/tegra20-emc.c index df758cebbd9d..0320d9df4a20 100644 --- a/drivers/memory/tegra/tegra20-emc.c +++ b/drivers/memory/tegra/tegra20-emc.c @@ -8,6 +8,7 @@ #include <linux/clk.h> #include <linux/clk/tegra.h> #include <linux/debugfs.h> +#include <linux/devfreq.h> #include <linux/err.h> #include <linux/interconnect-provider.h> #include <linux/interrupt.h> @@ -102,6 +103,10 @@ #define EMC_FBIO_CFG5_DRAM_WIDTH_X16 BIT(4) +#define EMC_PWR_GATHER_CLEAR (1 << 8) +#define EMC_PWR_GATHER_DISABLE (2 << 8) +#define EMC_PWR_GATHER_ENABLE (3 << 8) + static const u16 emc_timing_registers[] = { EMC_RC, EMC_RFC, @@ -157,6 +162,7 @@ struct emc_timing { }; enum emc_rate_request_type { + EMC_RATE_DEVFREQ, EMC_RATE_DEBUG, EMC_RATE_ICC, EMC_RATE_TYPE_MAX, @@ -193,6 +199,8 @@ struct tegra_emc { /* protect shared rate-change code path */ struct mutex rate_lock; + + struct devfreq_simple_ondemand_data ondemand_data; }; static irqreturn_t tegra_emc_isr(int irq, void *data) @@ -1003,6 +1011,87 @@ static int tegra_emc_init_clk(struct tegra_emc *emc) return 0; } +static int tegra_emc_devfreq_target(struct device *dev, unsigned long *freq, + u32 flags) +{ + struct tegra_emc *emc = dev_get_drvdata(dev); + struct dev_pm_opp *opp; + unsigned long rate; + + opp = devfreq_recommended_opp(dev, freq, flags); + if (IS_ERR(opp)) { + dev_err(dev, "failed to find opp for %lu Hz\n", *freq); + return PTR_ERR(opp); + } + + rate = dev_pm_opp_get_freq(opp); + dev_pm_opp_put(opp); + + return emc_set_min_rate(emc, rate, EMC_RATE_DEVFREQ); +} + +static int tegra_emc_devfreq_get_dev_status(struct device *dev, + struct devfreq_dev_status *stat) +{ + struct tegra_emc *emc = dev_get_drvdata(dev); + + /* freeze counters */ + writel_relaxed(EMC_PWR_GATHER_DISABLE, emc->regs + EMC_STAT_CONTROL); + + /* + * busy_time: number of clocks EMC request was accepted + * total_time: number of clocks PWR_GATHER control was set to ENABLE + */ + stat->busy_time = readl_relaxed(emc->regs + EMC_STAT_PWR_COUNT); + stat->total_time = readl_relaxed(emc->regs + EMC_STAT_PWR_CLOCKS); + stat->current_frequency = clk_get_rate(emc->clk); + + /* clear counters and restart */ + writel_relaxed(EMC_PWR_GATHER_CLEAR, emc->regs + EMC_STAT_CONTROL); + writel_relaxed(EMC_PWR_GATHER_ENABLE, emc->regs + EMC_STAT_CONTROL); + + return 0; +} + +static struct devfreq_dev_profile tegra_emc_devfreq_profile = { + .polling_ms = 30, + .target = tegra_emc_devfreq_target, + .get_dev_status = tegra_emc_devfreq_get_dev_status, +}; + +static int tegra_emc_devfreq_init(struct tegra_emc *emc) +{ + struct devfreq *devfreq; + + /* + * PWR_COUNT is 1/2 of PWR_CLOCKS at max, and thus, the up-threshold + * should be less than 50. Secondly, multiple active memory clients + * may cause over 20% of lost clock cycles due to stalls caused by + * competing memory accesses. This means that threshold should be + * set to a less than 30 in order to have a properly working governor. + */ + emc->ondemand_data.upthreshold = 20; + + /* + * Reset statistic gathers state, select global bandwidth for the + * statistics collection mode and set clocks counter saturation + * limit to maximum. + */ + writel_relaxed(0x00000000, emc->regs + EMC_STAT_CONTROL); + writel_relaxed(0x00000000, emc->regs + EMC_STAT_LLMC_CONTROL); + writel_relaxed(0xffffffff, emc->regs + EMC_STAT_PWR_CLOCK_LIMIT); + + devfreq = devm_devfreq_add_device(emc->dev, &tegra_emc_devfreq_profile, + DEVFREQ_GOV_SIMPLE_ONDEMAND, + &emc->ondemand_data); + if (IS_ERR(devfreq)) { + dev_err(emc->dev, "failed to initialize devfreq: %pe", devfreq); + return PTR_ERR(devfreq); + } + + return 0; +} + static int tegra_emc_probe(struct platform_device *pdev) { struct device_node *np; @@ -1058,6 +1147,7 @@ static int tegra_emc_probe(struct platform_device *pdev) tegra_emc_rate_requests_init(emc); tegra_emc_debugfs_init(emc); tegra_emc_interconnect_init(emc); + tegra_emc_devfreq_init(emc); /* * Don't allow the kernel module to be unloaded. Unloading adds some |